World of Warcraft worlock help?

I started playing world of warcraft about 2 months ago as a worlock, not realizing until recently that they're not very good to alot of people. but hes my main and i love him and dont wanna switch to my alternates. he's lvl 38 and destruction. any tips on making him better? will lvlig up help? anything that'll help me in battlegrounds against those god awful rogues! (knowing however that as a worlock im never gonna beat a rogue) what about better armor? which is better, increasing spirit, intellect or stamina? i have the money, im great at farming (only 38 and already 80g!)