I like to run a missile based Mobula (featuring artemis). I think I've won about 75% of the games I've piloted it. Here are some things I know that makes this "sniper" Mobula work.
1.) Squids
Before you start, make sure there are no squids on the enemy side. If you try to snipe against a squid, you will burn and you will lose. If there is a squid, forget about sniping. (Except maybe on chaotic 4v4s. Even then, if you see two or more squids, don't)
2.) Ship Loadout
Most common sniper ships are spire and mobula. Know that the guns don't all face forward. Put your large arc guns on the sides, and your little arc guns in the middle. I usually fly a Mobula, and I put hades in the middle, artemis to the sides.
Also, make sure you have at least one close range option. I recommend a carronade or a flame to disable the enemy and make a run.
3.) Tool Loadout
Your crew's loadout, unless they are completely outrageous, doesn't matter too much. You, the pilot's loadout, is essential.
Make sure you have kero or moonshine. Make sure you bring an altitude alteration tool. Don't bother with tar. I'll explain pilot tools later.
4.) Not too close, but not too far.
Obviously, you shouldn't fly too close. You are a sniper ship after all.
But don't make the mistake of flying too far. Your gunner will never snipe across maps. You will be useless. You need to fly close enough to consistently snipe certain components.
I usually fly under 1000m away. This will depend on your style, but never expect to hit outside 1500m.
5.) Talk to your crew
Whether your crew is experienced or fresh, they won't often aim to snipe certain components until you tell them. They will point to the enemy and hit the ship, especially at extended ranges. Tell your crew to target certain components. Even fresh crews will do that if you tell them.
6.) Talk to your crew
Your crew can usually adjust your rotational movements. They'll be leading the enemy if they are any good. But its hard for them to adjust to vertical movements. I'm not sure why, but it is.
Whenever you change altitude, tell your crew to adjust their aim.
7.) Pilot tools
There are far better players to explain how to use pilot tools. This is how I use them.
Kero/Moonshine - I'm turning, and I need to stop to give my gunners good shots and good arcs. I tap kero or moonshine to stabilize my ship.
Hydro - When enemy is coming for us, I like to change altitude. I like hydro better for this because, when I go up, I'm usually not hittable by gat/mortar. And I can drive over them and drop behind them. It's especially effective against pyras.
This is about it. This is how I play sniper and make it work. I'm sure there are better tips.
I have few maneuvers on a Mobula that I love, but those are trade secrets. (And I'm sure any good player knows them anyways).