Getting Exalted Orbs is an accumulation of many things. U can either a) flip and trade currency or B) you can grind.
If you want to grind then, IMHO as TS ranger, efficiency>quantity>rarity. Clear maps fast and efficiently. don't worry too much about MF (maybe get a 100/150 Bisco’s collar if you can fit it into your built and not die/still do damage).
Get to maps asap and get build working. Cap resists, get enough stats, get 3–4k hp as cheaply as possible. Use the POE trade website to do that.
Don't waste currency on marginal upgrades. Always prioritize upgrades by which will give you the most damage/ survivability.
From here on you can do a few of the following:
Bonus strat: (Might or might not work for you, I just did it for the fun) I bought all my end game gear by doing this strat. I spent 2ex to optimize my char to run Vaults / Arsenals in the shortest time possible (around 2:30 min runs). Melting the Vault boss in 10 secs was my goal. I collected the occasional divination cards drops there (abandoned wealth and the hoarder) there to exchange for exalts. Collected 5 exalts in about 25 hours just from cards. Sold all my other red maps / shaped red maps for chisels which I then turned to chaos and then more exalts.
Since you are semi-casual just slowly make your way up and enjoy the upgrading process. Think of getting your RoTC bow as a journey. It doesn't enable your build. Its the crown on top of everything else.
Hope you get there.
If you want to buy Exalted Orbs, try the following shops:
Buy PoE Currency Cheap