Here is all the info you need.
Spoiler It has been confirmed, via http://www.xbox360achievements.org/game/elder-scrolls-v/achievements/ that you can join either Storm Cloaks or Imperials.
Tactics: Imperials: There tactics are well known, they prefer a heads on assault, and with there massive forces this is a suitable approach.
Stormcloaks: There tactics are that of secrecy. They participate in a strategy known as Guerrilla Warefare (This strategy is a hit and run type strategy, confusing your enemy). This tactic suits small, UN-organized groups such as these Rebels.
Spoiler While helping whatever faction you prefer, you will be tasked with many assignments, and will go on Campaigns to take areas, such as a Fort, and a City.
These are not all fact, but from known knowledge from both Achievement list and Todd Howard, this is how i organized them.