You should never go 99 of any stat if your char level is not in the 90s. Its a waste of stat points. Only put to 99 if you need IC or if you have extra stat points to distribute. Otherwise, put in the other stats that you need, as you'll be getting more benefits out of it. Sniper relies on dex for damage so I would put more points into dex rather than agi. You can add some luk, but unless you're gonna go crit build, you shouldn't add too much. You can add a little int for extra sp and also to help with FA (if int does affect the dmg). Sacrificing a few job points to acquire FA will benefit you because it'll help deal some extra damage while you spam your other skills.