This strategy is specifically designed to break a turtle defense. The strategy base itself around pulling and "tanking". If executed right as low as 2 people can break even a ten man turtle. You need two people for this job (but the more the merrier), the first one will enter the FR (usually from balcony) and immediately snatch the flag, he/she will then exit the FR as fast as possible through one exit (relax, the point is to die for the first one). If all goes well most or all (preferably all) of the defense will follow that FC leaving the second player free to enter and camp the flag spawn. When the flag spawns he/she will instantly snatch the flag and exit from the other exit which should now be home free. This will probably take a few tries, but keep pulling back and forth. Sooner or later the turtle will break and from there on you're free to run home with the flag. There are many variations of this strategy, but this is the basic concept which can be carried out by all classes.
Simply not let them get away with tricking your team away from your flag, instead of sending all of your team to return it, just send enough to return it and leave the rest to deal with the next one coming.
This usually consists of 2-3 death knights... or more if you have them... and 2-3 rogues. The rogues spot the efc. One death knight runs into the open, distracting all the defense of the EFC. If on roof, this death knight usually pulls the FC away. While all the EFCs defense is after him, the other death knight/knights pull the defense away from the EFC. The EFC is now two death grips away from his defense. Now the death knight/knights quickly rush to the EFC and begin to damage. Now all the rogues jump out and use all their stuns, poisons, locks, and other such abilities to keep the defense away from your EFC. Why are rogues used for this Because they have more stun abilities than most other classes. But any class that can keep someone in place for about 20 seconds (might even take less if the DKs dps is high) can fill the spot.
This group is actually most often used to get people away from your own FC. It's risky because, unless there's a lot of heals in the match, there won't be many heals to stay with the FC. But it usually end up that way anyway. Basically, all the people with healing abilities... this could be the Rejuv of a Balance Druid or a Lightwell placed by someone... go to the base and keep lots of pressure on the EFC, simply because YOU WONT DIE. Of course because you're being kept alive you can take that chance to damage the EFC and often kill him, but again, just being in their base will (a) get their team off your FC or (b) get him to run away, hopefully separating him from your heals so that the one of your team that has the highest dps can kill him. It's risky and can often be messed up, but if it succeeds, yay.
Since only one can carry the flag at a time, you also only need one to enter the base. The best way to enter is via ramp as it is usually less guarded than tunnel, although tunnel does have advantages as well. What you want to do when carrying out this strategy is to dodge all opposing players, in other words not engage in fighting at all on your way to pick up the flag. Often the easiest place to stay out of sight is to hug the right wall when you are facing the other base (west for Alliance and east for Horde) and then enter through the hole in the fence by the ramp. Once inside the base it will often be smarter to enter from balcony as you are then better able to handle any potential defense. Grab the flag and exit in a way where the chance of getting detected/intercepted is the least. Remember you can only exit by ramp (go left), tunnel (middle) or graveyard (go right), where tunnel is usually the riskiest of them, but provides the shortest run. Remember that all classes can do this, but rogues and druids can stealth in for an even easier entry, and then use sprint/dash to outrun potential defenders. Once you're out you should either run home or to support, depending on the situation and your team.
Put a defender or two on defense whose main job it is to slow/cc/kill anyone coming solo to get flag. If they manage to exit make sure your team know where to intercept the flag to return it. While they are running do your best to slow/cc/kill that flag carrier while you wait for your team to show up.
This a relatively common strategy and it's based around the idea that as long as we are more than them we will kill them, and thus succeed. The basic concept on how to carry this strategy out is to keep all of your team together and alive, moving in the same direction and doing the same thing. Where you enter using this strategy is irrelevant as you'll probably have more people than they have defending anyway, thus you are able to both kill them and grab flag without problems. On the other hand it is important to remember that you don't actually have to kill anyone to grab a flag, and you don't need everyone killing either. What is possible is to start general chaos by attacking defenders and have someone exit with the flag in the confusion that arise, then have your team follow the flag while peeling of attacking defenders/returners.
Simply let them have your flag (losing a flag is not the end of the world), you can get it back later when it is easier to deal with them, instead go get their flag which will prevent them from scoring and do your best to prevent the zerg intercepting your flag carrier as he/she will most likely die fast should he/she run into them.
This strategy is very similar to soloing the flag, but you bring along a support to help with the job. Usually there will be a tank like character and a class with healing capabilities in such a group, however there is nothing wrong with other combinations if that's the intention. The attack itself is fairly similar to the solo attack, but the supporter (you should decide up front which character will carry the flag) should be ready to heal/dispell/cc/dps at all times. It is possible to do more attacking when two, if there are opposition chances are they are alone and can then be worth taking out. However remember that you don't have to kill anyone to get the flag, thus you should only start with killing opposition if it seems smarter than simply CCing them and running back home.
If the supporter is a healer you need to remember that any good healer left alone will be able to heal through most damage done in pvp, thus you cannot leave him/her alone. On the other hand he/she will then most likely start healing him-/herself leaving the FC free to dps you. The best way is usually to stun/sheep/fear/etc. the healer and take out the FC when it's without its support. If the supporter isn't a healer, you can simply focus fire on the FC for a quick kill.
Since both bases have different levels, but defense tends to all stay in flag room you can use this to your advantage. The entrance to either roof or balcony is very often poorly defended, if defended at all. By attacking from high ground you choose when the fight is initiated, and you also have the advantage with them being unable to run directly to you. Keep in mind though that all range can be used from the flag room and up to you if they have you as target, but if you then simply back out of line of sight you cancel their attack possibilities. AoE attacks are often very good for this attack. If you appear to be solo you can very often pull rogues/warriors/paladins out of the flag room if you attack them like this, leaving you open to jump and get flag with no defense. Another possibility is having a mage jump in from roof with 2-3 healers spam healing him/her while the mage AoE kill everyone in sight.
Staying in stealth/shadowmeld can help, if you get targeted by such an attack you should run to a place where you cancel their line of sight. Places which cancel line of sight could be under balcony, in the flag pocket or into the ramp room (keep in mind that you then lose out on some defensive capabilities towards the flag.)
Using this strategy you will be using 5 people inside your flag room. The aim is to prevent anyone of the opposing force to get to your flag and you will be killing everyone. There should be at least one hunter who frost/ice trap the flag, and other people in stealth doesn't hurt either, leaving defense with the advantage of surprise.
It is a relatively strong defense against narrow minded attackers. You have potentially a lot of damage dealing capabilities and possibly even some support.
Very similar to a 5 man defense, but using more people to do it. Your goals will be the same as when using 5, but now you have more people to do it which might make you able to cover more of your base and/or use scouting. You should still have a hunter (or several) trap the flag and people in stealth can help you as well. (if you decide that 10 people on defense is the way to go remember that you are no longer in any position of getting their flag, thus you are doing nothing but waiting to lose)
This is a large turtle and the best way is to use a turtle breaker, but you could possibly overpower them if your team is good enough/well enough geared. Keep in mind though that if you try to overpower them you leave yourself open for retaliation.
Using this strategy you will have one or two people on FR defense (and the rest elsewhere on the map) who's main job is to prevent anyone ninjaing your flag. Whereas they will never stand up to an attacking zerg, they will be able to provide information about the status of your flag and/or deal (up to) considerable damage to their flag carrier and/or hopefully kill/cc FC supporters. When/if a flag leaves your base with this strategy it is the defense's responsibility to tell the rest of the team where your flag is heading. In theory you could have any class on defense here as everyone can tell where the flag exit, but classes with high damage burst potential and/or slowing abilities are arguably better at this job. Stealth also works wonders here, meaning that classes like rogue and hunter are very well suited for this job (one very viable choice for alliance is a NE hunter with a cat in stealth). Remember that this strategy base itself around the assumption that someone will get your flag at some point.
Simplest is to use more people than they have and just take the flag, but considering that their team does probably have a strong midfield it might be hard to get a large force inside their FR making it harder to overpower them.
You can use a variation of the turtle breaker, since this strategy more or less assume that the flag will be caught, they will most likely follow whoever gets the (first) flag to return it, leaving you open for a quick repick, OR you can cc/kill them on your way out while your FC take a beating.
By opting for this strategy you free up all your team to be able to do other tasks, but you will also at the same time leave yourself wide open to even the lowest level and poorly geared beginner. However if your midfield is good, there are no reason why it shouldn't work. As most people simply aren't good enough and/or motivated enough to enter the opposing base solo, chances are you don't have to worry about your defense at all. Keep in mind though that having no defense you cannot provide any information about whether it is safe for your FC to enter your FR on his/her return. Also keep in mind that there are little to no point in defending your FR if you have already lost your flag, though if you know that the flag will be returned shortly it might be worth defending an empty FR.
Simply sneak in 1-2 people to snatch flag, if their midfield is too strong for simply dodging them you can stealth past them.