I'd start with a Soldier and then expand based on your interests (tech powers, biotics mixed with C.Q.C., etc.).

As a general rule, if there's a possibility of getting someone on your side, try diplomacy before you start shooting. I've read that the Galactic Readiness, the multiplicator you get for the multiplayer part of Mass Effect 3, decays in real time. Mass Effect 3 endings - how to get the best ending in Mass Effect 3. You could reach max readiness without multiplayer just doing side missions. For Mass Effect 3 on the Xbox 360, a GameFAQs message board topic titled ''You can get the best ending without touching multiplayer.' Mass Effect 3 had a multiplayer mode, tangential to the main story and tacked on thanks to a corporate mandate. Multiplayer and MEI (Mass effect infiltrator) are the only ways of increasing readiness. Read the guide to get the best ending for you, and happily complete this massive game. I would not at all be surprised to see multiplayer as a standalone monetized service or paid DLC.

Mass effect 3 how to get best ending