Your best bet to an exotic is to save your strange coins (doing weeklies or from the cryptarch from engrams) and wait for Xur to sell an item you like. 23 coins for a primary and 17 for secondary or heavy. You also could try your luck at an exotic engram for 23 motes of light but that's only a 33% chance it'll be for your class. The faction reputation is key too since there are great legendary items to be had. Check out the vendors to see what they have and also who's rep is currently highest to see who you can get level 2 and 3. At level 3 you can buy all armor and weapoms they have to offer. Then start running bounties like crazy since youll need 2000 rep for level 2 and 2500 rep for lvl 3 and each level there after. You'll need to run strikes or crucible to get the marks needed in addition to the reputation too. While doing all this you have a tiny chance to randomly get an exotic as well but I wouldn't bank on this. Once you get lvl 27 or so start running VoG raids too for legendary and exotic drops. Hope this helps!