Just got to my first Muton mission on classic and have no clue how to beat them. They freaking never ever miss, and can take soo much damage. It takes like 3 hits to kill one, and with how hard it is to get high percentage shots in this game, you are going to spend a lot of turns taking a group of 3 out. It doesn't help that I don't have my A team and my only sniper is out sick too.
This is probably a sign that I need to learn to use more of my abilities, particularly explosives and smoke.
I've also been doing less overwatching, since it seems like overwatchers always freaking miss and Mutons shoot like 100% so you can't waste turns sitting around with anyone. I guess it just seemed like my strategy of putting one or two guys behind full shield cover and just overwatch to keep those aliens in place as my other guys work to flank didn't seem to work anymore, and it didn't seem like it had any higher percentage then just shooting at the bastards. And now that strategy makes even less sense since full shield cover apparently means nothing.