(I HAVE THIS ON COPY N PASTE STANDBY) Why? Cuz this most asked question ever.
I have never once lost anyone, so long you use your brain
Fire Team Lead: Miranda & Garrus & Jacob only
Pipe Team: Tali or Legion Only
Shield Team: Samara(Morinth) or Jack only
Escort Crew Back: Doesnt matter, just send someone
When you start up the final fight, don't say: We have to Hurry(you raise the odds of someone dying)
Make sure everyone is loyal
Make sure your ship has major upgrades needed, Armor, Shields, Guns.
I now how 5 play throughs(playing every class in ME1, porting em over to 2 & playing), I have never once lost anyone yet, with this setup, ever.
1st playthrough, I sent Grunt Back, had Garrus lead both fire teams, Tali in the Pipe, Jack Shields. I took Miranda & Samara for final fight
2nd playthrough, I sent Grunt back, had Garrus lead both fire teams, Legion in the Pipe, Samara shields. I took Garrus & Zaeed for final fight
3rd Playthrough, I sent Jacob back, had Garrus lead both fire teams, Tali in the Pipe, Samara shields. I took Miranda & Legion for Final Fight.
4th Playthrough, I sent Jacob back, had Garrus lead team 1 & Miranda lead team 2, Legion in the Pipe, Jack on Shields. I took Mordin & Morinth for final fight
5th Playthrough, I sent Tali back, had Miranda lead team 1, Garrus lead team 2, Legion in the Pipe, Jack on Shields. I took Legion & Zaeed for final fight.
No one has died yet & crew has survived 100%
JJ