You have laser rifles, which have infinite shots. If you suspect hidden aliens, and have the patience, level the area with lasers until they are exposed. Use caution in terror raid because of civilians; otherwise, laser to your heart's content. Feel free to call in the big explosives as well; the only disadvantage is you probably blow up the alien gear if you do. (uncle briggs)
For the first couple of missions, rocket launchers are your "Oh Shit" mitigators. Use when things go south, and use liberally. Two aliens on a roof are a prime target for a rocket launcher. (JakeSolomon)
To be clear, I tend not to use the rockets until I feel things slipping away from me. I hate losing artifacts. (Unless we're talking Cyberdiscs on your first terror mission. Rocket them without prejudice.) (JakeSolomon)
Early on in non-Terror missions, you should be using explosives liberally. Rockets, grenades, demo packs, proximity mines. You can't hit the broad side of a barn with your starting troops and kit, so just focus on levelling the barn. Hopefully the aliens will get caught up with it. (Frith Fret)
2 aliens on a roof? High Explosives lobbed up there will level the entire top floor. (slantz)
If there's more than one alien near each other, use grenades. And when I say grenades, for my own tastes, I really mean high explosives. Huge difference. Prime, toss, BOOM. Gets shit done right. (slantz)
How do you use grenades effectively? Prime it to 0. Throw it at the enemy. It explodes when you end your turn. (jab and garin)
The only grenades I use with any regularity are proximity grenades, and even then only for base defense. There's a trick where you can play hot-potato with live grenades and ferry them up from the back, but it's risky. In TFTD I learned to appreciate smoke/dye grenades, but that had more to do with the layout of the Triton landing craft and having to deploy at ground level. (Alan Au)
Use flares if its by night to see the enemies. (TurinTur)
Auto-cannons with incendiary ammo set on auto-fire lights up the night (and hiding places) quite well. When you find an enemy like this, switch to HE rounds. I usually have one auto-cannon guy in each group/squad early game. (ElGuapo)
Sometimes I arm the scouts with grenades. They can usually prime and throw in one turn. Also for ship entries, a grenade primed to 0 will go off when a dead scout drops it, often killing the alien(s) waiting just inside the door. (uncle briggs)
I used to name low bravery guys names like "Curly," "Moe," or "Shemp" (so I'd be sure to keep tabs on them) and I'd have them hold grenades and walk into downed alien spacecraft as advance scouts. That way if they panicked at least they'd drop the grenades and blow themselves and maybe an alien up. (Charlatan)
I prefer to save time units for a "Snap Shot" instead of auto, since it takes less Time Units. You can use the buttons in the lower left to auto reserve time units if you did not know. (Malkroth)
And I pretty much only use auto-shot, it seems to just work. Where aimed or snap shot, not so much... (karnisov)
Don't get upset if your tank is blown up. The tank's whole role is to get blown up. As long as you find out where the shot came from, you have gained information. (peterb)
FUCK the laser cannon tank. That thing is bullshit. Take the rocket launcher tank. First turn (assuming it's a recovery mission and not a terror mission with civilians), deplane the rocket launcher tank and spend a few turns LEVELING EVERY FUCKING BUILDING YOU SEE. Leave your guys sitting in the skythingie playing Euchre while the tank knocks out enemy hiding places. (peterb)