Get one exotic armor piece and the rest legendary from whatever faction you can buy from. If I were you I would upgrade the exotic all the way, same with the legenday but not the last 3 Def upgrades since it costs rarer materials and even if it was maxed out it would only get you to 29 max. With that you should be around 27 or 28 and should start doing raids since the raid gear is what you need to get to level 30 when it's maxed out. BTW once you're level 20 you don't level by exp. Exp gives you motes of light now when you fill the exp bar. You level by how much light armor gives.

Do a bit of the Queens Wrath bounties. It will get you a legendary helmet, chest piece and sniper just from the missions you can play from bounties. If you get the chest piece you're set. Edit: If you look at my hunter I have the armor and the sniper.