any tips

A couple of the GLs are tanks, so them.

Had a hard life on the streets - Ezra, isn't a tank, but is probably the best non-GL tank in the game.

SET (Sith Empire) and L3 are both great tanks with a pre-taunt.

General Kenobi on a Gal Rep team is still a great tank.

Savage again, isn't a tank but in GAC with his omnomicron is a great tank.

The trooper tank (Shore is it?) has a pre-taunt and can heal up, so again is good.

A SEE team needs a tank in most situations.  To be honest though, anything with a datacron is handy here.

Morning Elizabeth! and Zombie both put in shifts for night sisters.

Baylan puts in a shift for his team, especially in GAC, especially especially with his current datacron.

Again, Piz Pez Paz puts in a shift for Mandos, especially in GAC.

Star Killer isn't a hard unlock.  Don't worry about it.