Tips for CoD: Black Ops?

I need some tips for online multiplayer for Black Ops. I am 3rd Prestige Level 31. My Killstreaks are Spy Plane, Care Package, and Attack Helicopter. My main class is AK74u with Reflex Sight, Python Duel Wield, Semtex, Willy Pete, Scavenger Pro, Sleight of Hand, and Ninja. The other class I use is FAMAS with a silencer, M72 LAW, Semtex, Willy Pete, Scavenger Pro, Sleight of Hand, and Ninja. My K/D Ratio is 0.49, which is terrible. I usually get a handful of kills each match, but a few more deaths than kills. I rarely get any killstreaks at all. I will be willing to change my classes and killstreaks. I usually play Team Deathmatch. I do not have much of a style or strategy. I get an okay amount of kills, so tips for more kills would be nice. I need tips so I don't die as much. I would like to have my Killstreaks as Spy Plane, Attack Helicopter, and Chopper Gunner, and usually get the first two, and sometimes get the Chopper Gunner. I could use tips for killstreaks and classes as well. I could use tips for style and strategies. Also, tips for shooting and aiming would be nice. Tips for cover and for each map would be nice as well. Also, don't say by playing more and practicing I'll get better because so far I haven't. I need to know what to do. Please give tips for as many as possible.