If you're bad at PvE, I suggest checking out 48 Beastmaster (58 Beastmaster), 61 Riftblade and 61 Tempest. This should cover all roles you have to play in PvE. 61 Paragon for better ST and 61 Champion for better AoE (although hardly ever used) would be a bonus. If you have the healing souls and want to play them, 61 Liberator and Libchanter as well. If possible, don't play the easy 1-button specs or try to move on from those ASAP.
With 3.7, 61 Warlord instead of 61 Paragon is an option, but the lack of Grasping of the Horizon will make some encounters harder to deal with.
Remember though, playing Beastmaster right is harder than playing Riftblade or Paragon right. Get Kalert and get used to that.