Never use dreadsteed as your mount when in a battleground , it makes you instant target.
Buy many free action potions , there are many rogues out there willing to camp you for the whole duration of a battleground.
Spirit healer is your friend , complete immunity for 30 sec if you die in the correct time and enemies cannot even see you!! Learn to enjoy it since 80% of a battleground duration you will be there.
Make a /spit macro. When you see a rogue try to use it on him before you die .It is the only thing you can do to him but it is not guaranteed it will work, most of the times when you will face a rogue next thing you will see is release spirit message.
And finally Voidwalker ! There is a bug when he does consume shadows that makes him move so fast like crazy ! Maybe enemies will not attack you if they see this silly thing and just /lol at you. So consume shadows with voidwalker while u can. (It will be nerfed next patch voidwalker wont channel this spell and he wont be funny any more :/ )