Yes, I did unlock "Create a Class' but I have no idea what it is. I know I saw the 'perks' but didn't know what I should get. To be hones, I don't know what is available. I haven't unlocked the AK47, yet. I don't want it anyway. I'll take an M4 over it.
For an average player like myself, unlocking the perks is critical. Once you level up close to 50(as said, goes up to 55), you pretty much have everything you need.
Perk 2 are the most important class of perks. Most popular should be the
stopping power, which adds to any firearms you use. Add this to guns like MP5, M16, or AK47, guns with plenty of stopping power already, and you'll be able to take down your opponent in a hurry. If your aim sucks(like me

), I'd recommend P90. Spray 'n' Pray baby! It spits like million bullets a minute.
UAV jammer is a very useful second perk(class). UAV Jammer makes you invisible on the enemy radar, and with my limited "skillz", I rely on this perk heavily.
Perk 1 mostly has to do with your optional explosives. You don't have any of these yet, but in order I select: 1) claymores 2) three frag grenades 3) bandolier(extra clips)
Claymores doesn't just help you pick up bonus kills, used effectively, it's a game(or match) changer. It could effectively cut off the opposition route(like the sneaking you mentioned), or simply used to watch your back.
Three frags will become useful once you get down with the maps. You cook'em before you throw'em, and you gotta know where "they" like to hang out.
Bandolier's absolutely useless for noobies. When you are on a roll, you can be assured that you'll have plenty of ammunition this way, but: 1) noobies doesn't live long enough to need extra ammos. 2) you can always pick up other people's weapons on the ground.
The third perks are not as important as the Perk 1 or 2. My favorite perk 3 is the
deep impact. This lets you shoot through walls, peoples. Great way to kill 2, 3 enemies with one spray of bullets. Since you like to snipe, another good one is
that hold breath thing, that I can't remember the name to right now. lol It gives you another couple seconds of steady to target your guy in the scope. I sometimes use the
deadsilence. It pretty much eliminates the foot step sound, so you can sneak up on the enemy.
On the noobie advice, I'd say don't use the grenade launcher/noob tube. My opinion is that red dot is critical for weapons like M4/M16, AK47, etc., until you get some experience under your belt. It helps your view tremendously, and your aim, too.
Pistols are hard to use in the beginning, but like the Legendary said, once you get used to them, you can take people out without any problems, though you can't expect to go up to a good player who has a MP5, face-to-face, and take him down with your silenced USP45(my pistol!

). I try to be sneaky, when using a pistol.
Sorry it got so long, but here are my recommendation on the primary weapons:
MP5 - Easily the best 1st gun. Open/iron sights doesn't obstruct your view much, and has better than decent fire rate, stopping power, accuracy. Holds a lot of ammo. Just remember to keep your enemy in close range.
M4 - M16's actually a lot nicer with the longer range, way more stopping power, but for new players, the lack of full-auto I think is too much. M4's like a slightly shorter range, less stopping power, but full-auto version of that great rifle. It's super easy to use with a red dot.
R700 - I know you like the Dragonov, and it seems every CoD4 snipers has a different favorite rifle. For me, R700 has top-notch stopping power, accuracy, and you don't have to reload a whole cartridge at a time. And the slow fire rate isn't an issue with a sniper rifle, so.......
Any way, that's my take on those guns.
P.S. Do use those plentiful of covers in the game. Taking cover is very, very important in this game. Like you mentioned, I've had plenty of "WTF! How in the hell did that guy get me!" or "OMFG, how in the .... am I supposed to kill guys I can't see!". lol It will get better. I hope you stick with it!
Edit:
I going to play again soon, but the really good guys are coming home right now so I might hold off. Don't want to get spanked too hard; it'll be too painful to sit down.
Don't even worry about that. Most of us, the experienced one's, we still get some really good spanking every now and then. OK, I'm lying, it happens little more often than that.
