What Artic said

with the SMG, just fire a burst, I used to kind of do some single shots, but that takes too long, and bursting actually works better, if you get used to timing it. I think I'd do a lot better, but I do not really like to use it. when I use the shotgun, I just try to rush forward, then shoot everybody before they can see me

I am not very good at getting a lot of kills, anymore, but I think that some of these ideas will probably help