20 is barely into the game to be honest. think is now you need better gear to get to the end game content. there are a lot of things you can do to get better gear but the guaranteed route is to level of your rank with either the crucible or vanguard.
for crucible rep play the crucible and do crucible bounties.
for vanguard rep play the strike playlist and do vanguard bounties.
once you hit rank 3 you'll be able to fully suit up with purples (although you may get some randomes along the way).
once you have purples you need to level them up. public events and the daily story missions are you best bets there.
do the weekly raid if you can to get strange coins to buy exotics from xur (only appears on weekend).
once you've hit 30+ you can think about doing raids.
honestly,.. the next expansion is just around the corner and will probably be out before you hit vangaurd rank 3. the way leveling works you'll be able to just skip the 30-32 levels if you go right to the next expansion which may be the best way to hit end game content for you.
