If you're sticking with an SMG then Long Barrel is a good one to go with to increase range a bit.
Remember to burst fire at long range though, or you'll waste a lot of lead!
It still won't be a match for assault rifles at longer ranges, but if you can catch 'em by surprise and get the first couple of bullets on target, you're in with a chance.
You'll likely start gravitating to certain attachments as you play more. I play with iron sights mostly but you may prefer Reflex, TF, etc. for example.
On the MSMC, the one thing that I pretty much use all the time is Extended Clip as I am more of a rusher and find the standard a little anemic. Long Barrel, Silencer and Quick Draw are probably my most frequently used after that in some combination.
40 Year old here, I find moving slow or guarding an area a lot more difficult than moving all the time. It seems people can jump corners, ads, and kill me before I can ever get off a shot. Because of this, I will always try to stay on the offensive. In past CoD's I was able to stay in an area and do well, but not with BO2.
If you guard an area, your twitch reflex must be good, if you run and gun you have more of a chance of catching people from the sides, back, on top of.
Just how I play these days!
OK guys working the MSMC with extended clip and fast mags. Any other all around good weapons I you suggest I work with/?