You should have unlocked the Strike Playlist ( icon on the world map ) by now. Do strikes appropriate to your level in order to gain Vanguard marks, you'll need these vanguard marks to buy vanguard equipment ( which should get you to Lv.31 ). In the process you may also get legendary loot good enough to use. Patrol missions will help you gain Vanguard commendations ( also necessary for buying Vanguard gear ). You can also do the crucible. Loot drops are supposedly good there. You will gain crucible marks and commendations here which can be used to buy gear from the crucible vendors. You can also join a faction. Equip faction gear in order to earn faction rep. This and crucible marks and crucible commendations will allow you to buy gear from them.