Basically, you have two strategies:

1. Be Invisible: Stealth and Full Attack, using Rapid Shot to make three attacks, at +17, +17, and +12. Restealth every time at no penalty. Because you’re sheathed, these attacks always deny DEX to AC, and they’ll be Touch attacks within your first range increment so they’ll ignore armor/shield bonuses as well.

2. Be Mobile: If you’re already visible, for whatever reason, Move and Attack. This is automatically a sneak attack, though it doesn’t deny them DEX to AC. It does, however, make your skill higher (+21). You can move up to twice your speed, and you can shoot at any point during the move. Due to higher skill, it’s probably a good bet to use Deadly Aim (like Power Attack but for ranged weapons, and anyone can do it without the Feat due to the house rules): roll at -3 (+18) for +6 to damage. You can also try to Stealth while running since you’re not penalized at all for full movement while using Stealth.

Your damage would be 1d10+9 and +4d6 basically always. With Deadly Aim, it’s 1d10+15 and +4d6.

Average is 28, or 34 with Deadly Aim. That’s per hit.

You can do Deadly Aim with option 1, but your skill would be +14, +14, and +9.

And you can save all your Grit Points for Quick Clear in case of a Misfire, although I would always keep at least 1 GP for the +2 bonus to Initiative.

If someone manages to get up into melee, you get the +4 Dodge to AC against any AoO—in case you fail Acrobatics—even when you run and shoot.

And if we work together, I will be doing the melee and you can shoot into melee without the -4 penalty