A lot of good advice in here, but to any newly boosted hunters seeking a short guide, here's what I did (I'm sure this can apply to any class)
1. farmed honor and got full Grievous geared by
- a. doing dungeons and converting JP to honor @500JP:250h
- b. doing BGs though if your battlegroup sucked ass like mine option a. is faster
2. found a 2s partner to do arenas
- a. lose streak to ~600 mmr
- b. start winning back to ~1200 mmr
3. get full set Prideful Gladiator gear
There's really no better gear for fresh 90 toons right now unless you pay for runs or get carried by a/your guild.