Few things to add.
1. Dont go mad spending in the shop. Ranking up after SSG1 gives you over 8K credits.
2. Ranking up gives you guns(UMP,PSG1,AK47)
3. Accolades/Titles increase your stats, give you credits, and special abilities like being able to hold dual Deagles.
4. Aim for the head. 9/10 you'll get it.
5. Low life=camp. Don't try and go rambo when your life is low.
6. Flank the spawns, as there will most likely be 2-3 snipers camping it up.
7. Hit marker with a sniper=Pull out secondary and finish him off. I've seen countless people die while spectating trying to finish them off with a sniper.
Hope I helped. If you want more help, like ways to flank the spawns, add me in game.