Usually I start off the match with assault rifles and LMGs with Extreme Conditioning to grab the high ground. After that, it depends on what strategy the enemy and my allies are using. If the enemy camps or uses UAVs, I stealth it with UAV jammer, shotguns or silenced SMGs. If they go on offense, I stick to assault rifles and LMGs. I snipe when I feel like it, which is not very often.
One general thing about my style is that I stick to close quarters combat. I play CoD Halo-style by jumping, crouching, and dodging. If I'm playing a map with long-range combat, I'll stealth it by crawling and sneaking. I'm a product of MGS, which is tragic because I don't own a PS3. I just replay MGS2 and 3.