MOUT McKenna is a complicated map with multiple levels and poor lighting conditions. It is also very small, resulting in a large number of surprise and CQB conditions. To work effectively, you MUST travel as at least a two man element, three or even four being best, but no more. Cover all directions, and especially watch upper windows. Try to seize objectives and defend them, instead of prowling around looking for a fight. Alpha and Charlie both are good spots to defend with at least two people. Bravo is a bad choice, and NEVER hide in the tower, the number of people able to place a grenade right in it is astounding.
Don't bother with tunnels in the beginning unless you're sure you can either handle opposition or get through them without enemy contact. One person can move through either tunnel, allowing one to flank any blocking forces.
Loyalty's best tactic is to either defend Alpha or rush into the Honor staging area from tunnels or through Gray building. Both have their advantages and disadvantages.
Honor should attempt to hold Charlie. Token resistance should be put up for Bravo, as it is almost even odds there (Watch for Loyalty members who rush into the objective). Hiding behind the ladder in the church is effective in this case. Also Upper Blue is a great spot to camp.
Keep your ears and eyes open and be ready to run or shoot at any time. Learn to use NVGs well, too.
You really got to use nades a lot and listen for the enemy's' footsteps. The SAW will also help you greatly, especially on MILES servers.
The best way to learn tactics for MOUT McKenna is to watch specialized elite-players in game. In the history the map MOUT McKenna has seen the rise and fall of many specialized clans like QRF, [F] and in the newer times - but with quite low fragrates - A4D. The only clan who has been non stop top-ranked since 2003 is [TAAH]-> "The America's Army Hospital". With thousands of hours of playing experience this map specialized elite-squad is the veteran among the McKenna expert clans. For learning tactical intelligence for the map MOUT McKenna try to watch a TAAH member playing on MOUT McKenna.