Wizard: "as for a threesome as long as its 2 girls and me, I really dont like to do it."
Its ok, we dont discriminate in this forum.
As for coop...my preferred strategy is that I run economy and the other guy runs military/scouting, although I can do either one. But, until military becomes important, and scouting is boring, I usually have my partner take care of building new fishing boats and making sure the water stays explored as well and that there are no idle fish boats.
In a 3 person coop, do 2 people on military/scouting (as described above), and one person on econ. 2 people simply cant run econ, because it will cause too many disputes. Put the best player on economy, and then the other guys on military. Get one guy to control military on one front, and the other guy on another front. That way they can both make the best of micromanaging each little unit, ie: CA dancing, etc etc, while the econ guy remains working on econ.
Remember as a military guy to always ask the econ guy when you want to do something big, like make a tech upgrade, or queue up some units. Econ guy is the ringleader of every coop game, he decides how much food goes where, what villagers go where, whether or not you should tool rush, etc etc. Tool rushing against a coop team is generally much harder, and in the event of a tool rush this is what I do...
Econ guy is responsible for running his villagers away, and thats it. One military guy is responsible for blocking the attackers using walls, and houses, and continuing to scout and look for safe places to rebuild. The other military guy is responsible for making units to fight the attacker.
In a 2v2 coop, the military guy assumes the build units position, while econ dude does walling, scouting, and rebuilding. In a tool rush, military guy is the one in charge, he says what he needs and econ guy gets it for him...since econ guy is busy rebuilding and resecuring the new base, military guy should be the only one with eyes on the battle...so if you play econ, listen to what your military general says and give him what he needs to flatten the attack (careful military guys, this is a crucial move)
Coop can be very fun, but sometimes I get frustrated that people dont do what I want them to do or what I think they should do. I will be the first to admit that unless Im playing with someone better than me, I can be a bit bossy...and if you are ever on my team in a coop, I will apologize for this beforehand.
Anyway, I hope this helped a little. I have a limited knowledge of cooping, but its a good break from normal team play and singles.