Been enjoying the LP but it hurts to watch the tactics.
On a night mission NOBODY steps out of the skyranger without having a flare. Throw them EVERYWHERE. LIGHT IT UP! If you don't you only have a small circle of visibility around you and you're just running into pitch dark asking to be shot. When you do that they will just take reaction shots at you as you run because darkness does not hinder their vision - and then you die. If a flare gets blown up by a grenade then throw another. Don't just run another trooper into the now-dark corner trying to get close enough to the alien to have it visible within your tiny little personal circle of light.
Use the time-reserve buttons - the ones in the lower left around the big green arrow button. Click the "auto-fire" button for example and THEN move. It will keep you from moving soldiers too far and then finding they're standing exposed and unable to even shoot back. I haven't tried it myself, but if you have the range-based fire option turned on then its clear you need to take fewer auto shots. You're not hitting enough with the low % to-hit and your troops are getting killed as a result, so take multiple snap shots or aimed shots instead.
When you first start turn 1 and don't see any aliens consider just skipping the first turn. The aliens will move and then when you actually start stepping out into the open they'll have a lot fewer reaction shots at you. When exiting the skyranger step to the first space at the top of the ramp, turn 90 degrees and then step OFF the ramp. Don't just walk down the ramp because that wastes time. It uses less time units and immediately reveals what terrain and aliens are to your sides. Consider giving your first two men in the skyranger a smoke grenade. Toss them out around the ramp and then you'll have SOME cover when you deploy.
Troops left standing in the skyranger are troops who are utterly unable to help you kill aliens or save a trooper in trouble. The more guns you can bring to bear at anything the safer your troops will be. Look 360 degrees around the skyranger to make sure that your troops aren't going to just get shot in the back by an alien standing near the front landing gear. That means that you have to move a few squares that direction because althoguh the landing gear (front or back) provides cover it also WILL block your line of sight.
You can't bring all of your troops out in a single turn but as you do you need to be examining the terrain - looking for where you can move your guys to COVER and then whenever possible use the terrain to your advantage. Watch the aliens turns to figure out what buildings they are in and where, listen for the doors opening. When assaulting downed ufo's as opposed to terror missions there are no civilians to open doors so it MUST be the aliens. You like grenades so blow stuff up! Don't storm into a buliding if you can just blow it all up with the alien inside. It's safer for your troops.
If you have to be in the open then don't stay there. Move to a position of cover if you can. Don't push it if you're already in a bad positiion. Fall back and wait for the aliens to move to where you can shoot at them from a position of greater safety. Not that that's always possible but a soldier just standing in the open is a target. The beauty of Xcom is how it allows you to use real-world tactics. You can still win just by storming everything head-on all the time but you'll go through a LOT of troopers doing that.