Can I ask what level you are? First thing you need to get is the Medical Kit, then unlock Resuscitation. You will earn major points by getting them two and using them. It will help you unlock gun attachments faster.
Anyways I like to play and just defend, I chill back and pick people off with my Assault Rifle. Try not to rush them, because you will get naded or picked off easy, just try picking off easy kills. I'm a level 23 and my k/d is 1.99, and I only have 11 hours played. So just take some of my advice and you will get better, don't play like it's Call of Duty either.