Pirate (Gunslinger) Guide.

I don't know much about Gunslingers. I just think that Throwing Bomb is pretty useless. You can max Float, Gun Mastery and Gun Booster.

 Spoiler

Took from Shrapnel (blitzkrieg) of AiKMS:
20 Invisible Shot (Max)
20 Gun Mastery (Max)
20 Backstep Shot (Max)
20 Fake Shot (Max)
20 Gun Booster (Max)
10 Float (Max)
11 Throwing Bomb

Also, I think that you should get Invisible Shot at 30, just one skill point. It's a great mobbing skill. :]