So far as I know, a neutral playthrough of Mass Effect 2 will force you to choose between losing loyalty for either (SPOILER)Jack or Miranda and (SPOILER)Tali or Legion. Even though you'll lose loyalty for at least two allies, if you play smart and make the right decisions, everyone can come through alive.

Should you complete all the ship upgrades, nobody will die in the scenes immediately after entering the Omega-4 Relay. Once the mission begins in earnest, so long as you do not select non-loyal members for specific tasks (SPOILER)(i.e., your engineering specialist should be Tali if you sided with her against Legion or vice versa) and they should come through. So long as you complete every other loyalty mission and (SPOILER)leave behind at least two of Garrus, Grunt, and Zaeed to hold the position before going after the final boss everyone should come through alive.

Really, in my experience, you have to be trying to kill off your allies to screw things up. As long as you do the relevant ship upgrades (cannons, armor, shields) and get loyalty missions for as many crew members as possible, it's hard to screw things up.