First off all, I would like to say this game rules.Im playing it from the first apearance and i can say im allways comming back after some time of not playing it.
Now for the main part: Tactics i use.
As i said earlier im playing this for a long time, but i never finished it.I noticed in 2.5 that i need to realy change my aproach on aliens.
I used to equip every soldier with a gun, some ammo, armor, medikit and IR goggles, but never gave them grenades (and now i see smokes can be realy usefull).I also noticed new weight affecting TU.So most people say snipers dont need to carry armor, but i still give them because in later game i use Coilgun (in hands of expert 1 shot kills blodspider).
I first tend to get lasers, but until then i use plasma weaponry (Mostly rifle).Also i rarely use rockets (not the weapon of my choice) and flame thrower.But grenade launcher is a must.
I try to let aliens come to me, and i try to prepare a ambush for them (allways 2-3 guys waiting for them).Maybe tats why i have my starting team still alive
For the base layout, I use 4 labs, 2 laser abtteries, 1 rocket, 2 small hangars and 1 large, 2-3 living quarters.For base deffenses i allways leave 3 guys in the control room (one with camera room)-2 to watch the hallway from workshop and one inside.Rest i send on the main entrance but from 2 directions.With 4 labs i manage to researyh everything in short period of time, and when i dont have anything else to research i sell them and use them for antimatter storage and 1 extra workshop.
When im using that aproach, all my countries are happy or atleast neutral, and i can take down lot of UFos if placed in eaurope.Also when i see a harvester aproaching the base, i send out one interceptor to lure him away (but to stay in the base deffense range) and send the other one to help.
If this helped someone, please tell me and if you have any advices for me, let me know.Im still trying to find a way to deal with armored Ortnoks (my greatest threat).