The Sith have troopers, and Earth has soldiers besides STF. The Jedi on the other hand came somewhat unprepared. There's maybe a hundred Jedi, and the crew of the ship they brought. 

The STF and the Jedi are in a "the enemy of my enemy is my friend" sort of position. The STF and Earth's other militaries make up the largest part of the planet's defense against he Sith. 
The Jedi consider STF to be borderline Darkside, however galactic exploration law forbids them from actively influencing the ideology of newly discovered planets. That doesn't stop them from trying to teach their own doctrine when STF members and Jedi are on missions together. 

After some negotiation, the Jedi have been permitted to train young Human children in the ways of the Force. They are, however, not permitted to take them away, or to use them on missions. All training is done in special classes in schools. Unfortunately for the Jedi, the Sith have already ruined any trust and goodwill that the Humans might have had for aliens. Upon turning sixteen, however, it has been agreed that a Human can make the choice to permanently join the Jedi order. 

CS, feel free to fill it out and post it here. Please don't get offended if I knit pick in the beginning, as there are still ideas in my head that I haven't articulated for you fine folks. 

Name:
Age: The Sith and Jedi have any age(though Human Jedi must be sixteen), STF only accepts people age eighteen or older.
Species: STF is all human, the other two, all species are fair game(unless you come up with one I think is unfair in some way). 
Faction:
Rank:(Jedi have Padawan-Knight-Master and Sith have Acolyte-Lord. STF use normal human military ranks.STF have an automatic officer designation of Second Lieutenant or higher). 
Appearance: I love pictures, personally. Anything goes, however, as long as you describe your character in some way. 

I actually do not ask for bio or personality. Both can be expounded upon in character. Just don't over-use expositionary prose.