Getting this takes a bit of effort because it requires a lot of game play.
* You must use the Omega 4 Relay immediately after the crew is abducted. If you don't, there is a slight chance a crew member will die. So all tasks must be accomplished before retrieving the Reaper IFF.
* Loyalty missions are a must.
* When there is a fight between crew members, you must make peace between them or not take sides.
* You must upgrade all parts of the ship (with the exception of the medbay). You get upgrades by doing loyalty missions (Garrus, Jacob, Samara, and Tali).
* Certain characters have upgrades specific to them. Upgrade them.
* Selecting the correct squad members for the Collector base.
- I generally use Tali on ventilation, Miranda on 1st Squad Leader, Samara on Shield, Garrus/Miranda on 2nd Squad Leader, Mordin/Jacob on Escort, and my final team has varied (usually Mordin, Miranda, Jack, Kasumi, or Tali).
- The following characters will work (from what I've researched, for those who don't care for my line up):
-- Vents: Legion, Kasumi, or Tali
-- 1st Fire Squad: Garrus, Miranda, or Jacob
-- Shield: Samara/Morinth or Jack with improved implants
-- 2nd Fire Squad: Garrus, Miranda, or Jacob
-- Escort: Mordin is ideal, but Jacob also works
-- Final team can vary, but it is advised to leave two offensive characters behind (like Zaeed, Garrus, or Grunt) for a higher probability of survival and take characters with more defensive abilities into parties (like Mordin, Tali, or Jack).