1. Own a Spirit Beast. Seems simple enough--but getting a Spirit Beast can be a pain. The heal, though, is something you should macro and bind--with a modifier for Focus or arena-mates, if possible. You don't need to use the Spirit Beast in every situation--although I often do--but it's definitely a must-have in many cases. The heal is very powerful, and the damage buff is quite literally second-to-none (equal to that of the Cat). In other circumstances, I also recommend the Chimaera and the Silithid, and more situationally the Bird of Prey--especially if you are low on Resilience. Their ability to help you kite and to come to your aid with Roar of Sacrifice (which, like Spirit Mend and the Silithid and Bird special abilities, you should take off autocast and macro) is extremely helpful to your survival if your gear isn't quite up to scratch yet. Once your gear is decent, though, a Spirit Beast's heals, family skill + damage-boosting talents will really help you blow **** up.
|Note the duration of the fight, and the healing done--Shiver is my Spirit Beast. This healing is all Spirit Mend.|
I use the following macro, but be aware that you'll want to pick the Spirit Mend icon specifically rather than the ?, because otherwise it will show as a ? when the pet is away.
#showtooltip Spirit Mend
/cast [mod:shift, @focus] Spirit Mend; [nomod, @player] Spirit Mend
This casts Spirit Mend on me, or on my Focus when I hold Shift while hitting the keybind for it. Incidentally, also do this for other pet abilities, be it Master's Call, Intervene, or Roar of Sacrifice.
2. Coordinate your CC and your burst. It may be hard to hold back, but blowing all your cooldowns into that mage will go poorly if the mage turns into an ice cube. Wait for the opponent to blow some defensive cooldowns--or if it's going to be a close fight, burst early to force defensive cooldowns, and then play defensively yourself until you can burst again; BM cooldowns are relatively short. Hold back on burst in arena until your Freezing trap is ready (assuming the fight is longer than one BW), and control the teammate in advance--getting CC'd one second after blowing BW is not pleasant. Also, try and save Intimidation for your burst--just as you pop BW, to prevent defensive cds, or use it to stop the enemy if they try and LoS during BW.
If for some reason you need to try and CC the dps and nuke the healer, use Intimidation just after you CC to delay the CC being cleansed. Lastly--consider saving BW as a second trinket against CC-heavy teams who rely on CC + Burst coordination, especially if you have a partner who can put out pressure. Just remember to use your trinket first, and then your BW, and then you can burst. You can often get a healer out into the open if you and your teammate retreat across the arena; the DPS will follow, the healer will follow their DPS, and you can CC the dps and switch hard to pop everything into that healer.
3. Build up full focus before popping BW. Blowing your biggest cooldown and then needing to shoot off Cobra Shots, or blowing BW at half focus and finishing out of focus with your enemy at 10% and Kill Shot on cooldown--these are not pleasant circumstances. Also, unlike in PvE, where you'll want to save Rapid Fire for recharging focus after a BW, you can pop Rapid Fire during BW if you're hell-bent on scoring a kill.
4. Keep Mend Pet up at all times. I mean, ALL TIMES. You should be specced for Imp. Mend Pet anyway, and this will clear CC on your pet as well as heal it (just beware of UA and VT being placed on your pet by saavy casters). Hopefully as BM, you'll also have it glyphed. Use Spirit Mend on every single cooldown on whoever is being hit--the heal is powerful, and the cooldown is short. DO NOT send a pet out of LoS without Mend Pet on. Also, keep Cower on the pet's bars, and use it early if the pet gets focused; don't be afraid to pull the pet back to let Mend top it up. Don't be afraid to use Spirit Mend on the pet itself if it's getting focused, either! Remember, too, that your pet's Growl can be used to taunt enemy pets who aren't set to Passive. You can Growl Grounding Totem as well, simply by pressing Growl as soon as the totem drops, regardless of which enemy your pet is on (assuming it's in range).
Also, one final note--remember that, if your pet is getting focused and is likely to die, you can DISMISS PET, and then (once you're far enough away that it won't get one-shot when resummoned) call it back out. This isn't a good idea if there's tons of DoTs on it, since the pet will likely have only a few thousand HP for several seconds after being summoned and the DoTs may kill it before scaling adjusts its hp to full. That said, if you have more than one of the same type of pet with you, you can simply dismiss the focused pet and call another. TL;DR, your pet should NEVER die--it is half of you, and if it dies, you will die too.
5. You can Tranquilizing Shot without breaking CC. Take advantage of this. In a duel, for example, you can trap a mage or paladin and purge off every single buff--and you should. It will either force an early bubble or trinket, or you'll strip off every single buff and be able to Tranq off Avenging Wrath or other nasty buffs & procs before they become problematic (having already removed trash buffs you'd normally have to peel off first). Remember too that Tranquilizing Shot removes Enrage effects--so Tranq off a Warrior's enrage the second it appears.
6. Feign Death! For those who don't know, this drops your enemy's target. A brief Feign Death can give you several seconds of uninterrupted burst while your opponent struggles to retarget you. This is especially useful just after an enemy triggers Snake Trap, or as an interrupt on an offensive cast. These are both nasty tactics, and quite effective ones--and I sadly see very few people using FD in PvP videos. If they've aggroed the snakes in your trap, they will have to manually click you or tab through ten or so snakes first (assuming they don't have a /targetlasttarget macro). Using Feign Death versus a Warrior after you've Disengaged is also a good tactic--they will almost always charge your Disengage, and the Feign will often give you just enough time to outrange that--or to drop a trap. Or, you can Feign after the charge, leaving the warrior hitting Tab while you regain range (this is also a good time to pre-emptively Master's Call). Remember though that, in duels, party members will not lose their target on you if you Feign.
7. Use your pet to pressure. If you have to Deterrance, continue to use your pet to harry the enemy. The same goes for if you need to LoS or bandage, or anything else. You can also leave your pet on a healer while you hurt the DPS--you can Kill Command the healer for pressure and use Intimidation at will as an interrupt, and prevent the healer from drinking.
8. Disengage is awesome. You can leap off a bridge or cliff and Disengage right back, and sometimes your enemy will leap after you. Practice first--duel or trap a lowbie mob on a ledge and try it. You can also use it to chase your enemies, and you should practice at this, too. Disengaging after someone and Kill Shotting them while flying through the air is great, and even if you don't score a kill with it, it looks really impressive--and in the end, isn't that all that matters? Remember, you can use it to cover ground any time you're in combat--so feel free to get into combat if you're somewhere where you want to move quickly without mounting. Throw anything at a passing enemy or critter and spin-jump wherever you're wanting to go. Oh, and you can get into combat on top of a cliff, and Disengage at the bottom to avoid fall damage, assuming it's not too far to lose combat--for example, you can shoot someone at Lumber Mill in AB, jump, and Disengage at the bottom. Keep this in mind if you manage to get hit by a knockback on a ledge--or if you're quick enough, you can Disengage right back to the ledge.
9. If you're at low health and you come up against another hunter, sit on them. No, seriously. Run into melee range, Wing Clip and keep them close; Disengage after them if they use it. Drop traps for Entrapment, Concussive if they do get range, and close the gap. You can still kill them with your pet, and if they can't shoot you, they can't kill you. This is mainly a tip for a BM hunter fighting against a non-BM, but if the enemy hunter is also Beast Mastery, try and taunt their pet with yours before putting your pet back onto the hunter, or CC the pet if you can. With Kill Commands and good counter-kiting, you CAN kill them. Remember, you have almost identical cooldowns--so if they Scatter Shot you to get range, Scatter Shot and run right back! Fellow hunters rarely expect this, and often don't know how to counter it. You can also use this tactic as a recovery period until your defensive CDs are ready again (mainly Feign Death and Spirit Mend). Just remember, keep Mend on your pet to cleanse any CC the hunter may throw at it. You can also use this tactic if your CC is on cooldown and you're wanting to nuke a different target, and the hunter is trying to focus you; if you're very good you can keep pressure on your secondary target while preventing the hunter's damage through counter-kiting, all at once.
10. Don't be afraid to trap + bandage. Obviously, wait until any DoTs are off you before doing this, and preferably force the enemy to trinket in advance. That said, you can try to force a trink (or bubble or block) early by trapping + bandaging even if you don't really need the heal.