Be prepared for the unexpected! Have at least one tech specialist & one biotic specialist
It would be wise to gather Intel before jumping into a mission. The last thing you want to do is get yourself & your squad killed! Your team counts on you to lead them through adversity, so gather as much Intel about what & who your against. Now lets say you're ordered to recapture a stolen frigate from the geth.. now,knowing that fact that geth are synthetics, it would be wise to bring at least 1 tech specialist with you, tech specialists are very effective against synthetic shields and armor.. not to mention they can also convert synthetics to fight for you! Bring a biotic too! for you should also keep in mind that there could always be something unexpected waiting around the corner.. lets say cerberus was outside just waiting for you to finish the job for them, and when you least expect it... BOOM! sneak attack from behind.... so always be prepared & gather intel is the bottom line!