So what is everyone's standard multi player squad set up?
I'm loving dual snipers, both with laser rifles, scopes and one with skeleton armor. Supported by four rookie soliders with light plasma rifles and scopes.
The dual snipers usually catch people off guard. Skeleton suit primary sniper climbs the nearest truck, grave, building, anything to get a good vantage. Second sniper runs into a far corner of the map to get a good flanking position. Do not reveal them till you find a juicy target; let the rookies smoke the sectoid scouts.
The other four men spread out to locate and engage the enemy. Never rush (except in the first turn or two), always move and over watch. Light plasma rifles with scopes are VERY accurate, and usually do 6 damage per hit. If they're kept together over watching each other then even a muton brute will drop before reaching their target.
Keeping the snipers on over watch too (once they've fired and revealed themselves) means you men are very tough to reach. The secondary sniper's detecting grenade (can't remember its name) is also a very powerful tool and actually usable as he's normally closer to the front line.