Would someone please help me in ME2?

You do need the ship upgrades, otherwise team members can die on the approach to the Collector base. The ignments during the mission are mostly self explanatory, except I would recommend you send Mordin (the salarian doctor) to escort the crew members back to the ship because he dies very easily during the fight at the end, while you're fighting the boss. To go through the ventilation thingy you need a tech expert if you want them to survive. There are at least two of these, you should know them. You have two who are really good at biotics to do the shield thingy, just pick one. And to lead the two squads you need someone with leadership experience in his or her past ideally, and you can use the same person for both if you want. If you've been paying attention to things then you know who you can pick for these jobs. ;) It doesn't matter who you take on the other missions pre-endgame, just make sure everyone has loyalty, you have all ship upgrades, and you defeat the end boss as fast as you can. The nuke launcher is great to shave a lot off his health at once. Also, if you want the very -best- ending, you can only do Legion's loyalty mission after you go to the derelict Reaper, and nothing else. That way, all kidnapped crew members will survive too.