I don't exactly how I'm going to organize this. I envision starting by describing the pros and cons of each figure and weapon. I then want to discuss the variety of fire options- covering, suppressing, grenades, rapid fire, spread fire, etc, etc- and how to use them effectively. Finally, I'll probably conclude with situation specific tactics, and general tactics for each race.

In the meantime, I do have some tactical advice.

Keep figures spaced, but supporting. If a figure takes a shot while moving, they should kneel and let someone move up behind them to provide covering fire. FIgures should always stay in pairs, and should be positioned in the tunnels so that they can't be flanked.

Suppression has to be handled carefully. Always activate suppressing figures last, so that your troops can move through suppressed fire lines without getting shot. Suppressing is best used by the Machines in long corridors (preferably 8-10 squares from any entrance, so that displaced thrown grenades aren't an issue) and by UNE, not at all.

Suppression should mainly be used on the defensive. It is not all powerful, just useful. The best way to perform suppression is to have a kneeling figure suppress, with another figure behind them, either suppressing or covering. Preferably two figures, one suppressing and one covering. If you to have suppress the entrance of room, and there are other entrances, have additional figures provice covering fire so that someone doesn't sneak in and shoot the guy doing the suppression. The advantage of supressing is you can fire at anyone who enters your suppression lane. The disadvnatage is you can only fire at someone who enters your lane. Covering fire is more flexible at who you get to shoot at.

Leadership (especially in the basic game) is very important. The Machines can limit the effect of Leadership by killing off non-coms, of course, but there are other tricks. Don't use covering fire on a commando until he declares his intent to fire- that way, even if he uses Leadership to move out of the way, he either has to spend another Leadership to move back into line of sight, or waste his own shot.