I am a lvl45 Sin that wants to be able to solo FF
I'm doing my stats 1 str 4 dex every lvl

I was wondering what skills i should max and what skills i should leave at lvl1 or when to stop lvl skills

Currently on my sin (lvl 100) I have maxed:

Just for fun:
Slipstream strike
Puncture Wound

What you should Max and what I have maxed/Will Max:
Deep Sting
Rib Strike
Throatcut
Earthen Rift
Headhunt
Subsea Strike
Power Dash
Dagger Devotion
Sharp Observer
Cat-Like Tread
Tidal Protection
Shadow Walk
Focused Mind
Shadow Escape
Blood Paint
Wolf Emblem
Knife Throw (For Range)
Tackling Slash
Inner Harmony
Windpush
Shadow Jump
Maze Steps
Shadow Teleport

You don't have to max the following, but if you want... w/e:
Chill of the Deep

Everything else leave at lvl 1

looking back at this i should have wrote what to leave at lvl 1...

would make it a lot shorter... <.< o well.