as othes have said, check around the archives and look at the timeline. dont go starting any uber-invincible super destroyer fleet led by a lightsaber weilding sith master (true story!!) and youll be just fine.
do whatever you want. all paths have a great mentor with them. you can find me currently sleeping rough at the feet of TJO, but eventually ill get higher!
My advice , which you are perfectly at liberty to ignore, of course, is to have a look around get to know the factions and the people involved , before you commit yourself...
I still lobby for some NIFers joining TNO. Lance, you'd be perfect for the ISF. Besides, the Coalition already has enough RPers. My Special Forces division is made up of, well, me. And occasionally Vaseli.