What's been driving me mad recently is how quickly my tanks are downed. Literally, 2 shots from an alien's weapon and the bloody tank explodes before I've even moved it far enough away from the ship to risk levelling some buildings.
Tanks are useful in the early game, not so much later. Your average recruit has 60TUs. In the early game, it makes sense to use a tank as a scout - they're plasma magnets and relatively decent shots. Later on, some of your more impressive soldiers will boast 70, 80, 90 (maybe even more) TUs, pinpoint accuracy, and with extra abilities such as mind control - it becomes clear that 4 (hell, sometimes maybe even just one) of these dudes is always better than one tank, even if it is a hovertank
Mini squad all working together means they get promoted quicker
If you care about your soldier's ranks, you should hire more guys. If like me you decided to stick with your 8 starting soldiers, then they won't get promoted much past Sergeant. A commander (top rank) will only appear if there are 32 (might be wrong on the exact numbers) men in total to command, for instance. The game won't just promote your guys for doing well, they must also have some people below them to command
Also remember that your Lieutenants, Captains, Commanders and other officers will increase the moral of soldiers by their very presence... on the flipside, these rookies will be absolutely devastated if 'Colonel Carlos' were to get a plasma round in the back of the head
Try to get anyone off the ship and they'll be taken out by reflex auto-shots by waiting Mutons
.Re: alien races -
Sectoids and Ethereals are the only races which can mind control your soldiers - it also means they're the races you're going to need live specimens of (to interrogate) in order to unlock the relevant research so you can do your own mind tricks, so good luck!
Sectoids go on terror missions with cyberdisks, which violently explode when destroyed. You can use this to your advantage. Shoot the discs first, especially if they're in a petrol station = KABOOM
Ethereals go with some huge robots which somewhat remind me of mechwarrior. These guys are tough to kill, but a tip - take a laser rifle with you if you know you're up against Ethereals on an alien base raid/terror mission. Whilst the robots soak up plasma, laser fire screws them up and kills them faster despite not being as powerful. Ethereals, on the other hand, are frail - however their mind control is even better than the sectoids.
Floaters (and their terror dogs) are pitiful. A mission against these guys is a good rest.
Mutons are ludicrously well armoured. Heavy plasmas mandatory if you want to punch through their armoured skin.
The "bail out" advice for Terror missions is invaluable. I hate them. HATE THEM HATE THEM HATE THEM! My squad invariably get their damn stupid asses handed to them. Now that Chrysalids have shown up in my playthrough, "rape" would be an understatement.
Even in Power Suits they're getting creamed.
Now I just land, send one guy out to check out the nearest enemy type (he usually steps out, looks, and get shot), then dust off!
Snakemen are rubbish, but their terror buddies (Chryssalids) are scary. These guys have 120TUs (sometimes more!) so they run around for AGES and you'll all be familiar with their one-hit-kill-and-zombify attack, which they love to do to civilians to make your job that much harder. Shoot immediately!
You'll notice when you shoot a zombie he just turns into another of them bloody things. My advice is to only open fire on a zombie when you are SURE that you can kill the Chryssalid that will pop out. The zombies
don't have 120TUs, so make sure you can get a kill before you turn him into something even more terrifying
On a side note, you've finally done it. I'm now reinstalling this!