I personally think that the 30's range, apart from doing STV and Desolace quests, should be all about running instances. RFK, SM, and then RFD when you get close to 40 are all your best bets, if you can get groups. It's a great way to be leveling and not even think about how much xp you're getting.
Only other tip I know of is to get a leveling buddy, if you know anyone around you're level. Leveling goes a lot quicker and a lot smoother when there's another person motivating you. I absolutely HATE soloing, so that's probably my problem there, but... Hm.
Anyways, good luck. The 40-50 range is a pain in the arse; if you're having trouble in the 30's, you're not in a happy place.