If you are boat fishing then you want 30 - 40lb braid with a shockleader of 20ft or so (Twice the length of your rod plus a few turns round your reel). The choice is yours. Might I suggest that you use braid and not Fire Line. (Rubbish)
I generally use 40ld as my traces are normally 30lb, however my spare spool is loaded with 30lb so that I can change, whenever, although I never have done.
Before using braid it pays to check the rings on your rod for nicks, these will shred it to ribbons on your first drop.
Never had a problem with Fireline myself - though it pays to take care when tying knots as they can slip more than 'normal' braid - due to the smooth coating.
Gulle where are you fishing? - the other thing to consider is if you want a level wind or not. Some people prefer to use level wind reels with braid as it's easy to slice through a cold thumb when trying to spool the line under load.