first i'd like to warn you. i've only just started playing bfbc so some of these tips may be a little noobish. but i dunno.
gold rush tips:
attacking:
i) if there is one. try to get into an artillery cannon. it yields lots of kills
ii) if you are used to gtaiv helicopter controls DO NOT FLY THE HELICOPTERS,
it is recommended you change the controls as they confuse the hell outta me.
iii) if you in a troop transport vehicle. (e.g humvee) try to stick near a tank or some troops for cover/support.
iv) check for anti tank mines. ive seen loads of people suckered in by them
v) guys with rpg's could easily take down a tank. if your sniping take them out first.
defending:
i)try not to stand right next to a gold crate. these tend to be targeted by tanks/rpgs or mortar.
ii) hijack helicopters. these can be extremely useful.
iii) use the support class to heal your team
iv) find a good spot in the hills to snipe enemy rpgs
v) use the support class's mortar strike along with the anti tank mines to bring down tanks
capture points:
stay out of sight. most teams wont know if someone's attacking a flag unless they are there. unless you've been seen of course.