The Burning Crusade Hunter Proficiency and Experience
4.1 Level Management
If you're planning to stay in a BG bracket for a while, experience management becomes non-trivial. Pre 70's, at some point you'll have to start throwing away many marks of honor in order to avoid levelling up. Players who stay in a bracket for a long time will tend to have just a sliver of experience less than that needed to level (and generally they'll stay in the bracket until they accidentally level up such as through discovering a new land).
It is also very important that you plan ahead as to what instances you need to run in order to get your loot. You do not want to be lvl49 with 100 experience to levelling, and then find out that you forgot to run Mauraudon and now no longer have the option. In this case, you will have to settle for being less equipped than even a poor hunter who just ran Mara a few times and got the exceptionally good hunter gear from there.
4.2 Pet Experience
One additional headache for hunters is managing pet level and loyalty. PvPing with your pet will not increase its loyalty. The exact mechanics of how pets gain loyalty is not known, although it is some combination of keeping your pet well fed and grinding mobs that give experience. Fortunately, keeping your pet happy is easy through BGs because everytime you resurrect or hit a restoration powerup, your pet gains happiness. However, beyond a certain point, your pet will not gain loyalty unless it is grinding or gaining levels -- you can keep it by your side through months of BGs and it will not gain loyalty. This creates a particular headache to twink hunters who get a pet late and cannot level it up beyond some loyalty point because they cannot grind mobs for experience.
Note also that your pet does not gain experience from your rest bonus nor from your quest turnins. Thus, to keep your pet as close to the same level as you, you will want to grind off of rest bonus. This really only becomes an issue when you have reached the level you want to stay at (e.g. 19, 29...), have gotten a new pet recently, and want to level it up as much as possible. Once you start approaching the level at which you want to play BGs, you may want to consider minimizing your rest bonus such as by quitting outside of inns and cities. This way, you have the best chance of leveling up your pet without gaining too much experience yourself. Bear in mind that your pet does not gain experience from quest turnins (such as turning in marks of honor).
4.3 Weapon Skill
Read more about weapons skill at Wowwiki ( http://www.wowwiki.com/Formulas:Weapon_Skill ). Weapon and defense skill affect a number of combat stats. The actual contribution of skill seems to have a lesser effect in PvP than in PvE. This much is obvious because otherwise in PvP you wouldn't be able to hit anything more than 5 levels higher than you, and your spells would always be resisted. Regardless, you will want to get these to their maximum values if possible, and weapons skill is still very significant. This can be done simply by grinding through grey mobs or letting them hit you until your skill is high enough. You can use cheap intellect scrolls during this grinding, or pay a mage to buff your intellect.
Note that the higher the level of mob you interact with, the more chance you will gain skill; that said, you can certainly grind grey mobs until your skill is maxed out, it just takes a lot of time. When grinding mobs in this way, I put on some grey weapons and spam rank 1 wing clip and scorpid sting since those inflict minimal damage. If you're getting tired of hitting low level mobs trying to skill up, get another character to allow you to follow him around and hit mobs that he's already tagged. In Stormwind Keep, while I'm waiting for BGs to pop, I will skill up on Onyxia's elite guards there, once someone else has tagged them. Sure I'll die occasionally if I accidentally aggro one, but it's also much easier to skill up on that way than to grind grey mobs forever.