It's not even "bad spot". It's that nobody can literally hit the target to save their lives. I had four guys at medium distance not being able to land a single shot on single alien, ten he killed two on his turn. Or sometimes I hit, sectoid survive and one-shot back. If armor will make it possible to survive one shot, it will be possible to heal solider back with medkit or at least retreat.
Sending a tank forward helps a lot, though. Maybe I should use two.
A tank can help in the beginning, if you can afford the price.
The most efficient way to win firefights in UFO is to use a spotter-sniper system: secure an area (easier said than done, you might have noticed that getting out the Skyranger is sometimes quite a feat), choose some good shooters with heavy weaponry (Heavy Cannons with HE, Incendiary, Laser guns) and then cover ground jumping from cover to cover with rookies, scouts or tanks. Try to keep the FOV open for the snipers. Identify targets, annihilate targets. If you have to fight in urban areas and you are sure that there aren't civvies around, level the places with grenades: better safe than sorry.
I know, it's kind of a slow method. But in the beginning you will win some missions and learn the ropes.
Armor and medkits do not work like in most games: a medkit heals only stun damage or "wounds", and cannot be used to regain health on the field.
Armor is less important than a good position, squadmates and firepower. Case in point, in my last mission, a vet squaddie in power armor after missing six Heavy Plasma shots against a Muton two squares away, was shot dead in a single hit by the aforementioned Muton with a single Plasma rifle hit. Say goodbye to 120'000 $.
EDIT: Wohoo, Follow the Brazilian lead. They did well in Italy, I've heard. And tell us what do you think of the Snakemen terror missions after you find one:
I'm very curious.