The two replies are both good.
However, understand why you are interested in “sniper fits”. If it’s by analogy to games such as Call of Duty where snipers hide at long range plinking off unsuspecting victims, then that’s not a good comparison.
An active ship in combat can’t hide. “Sniper fits” are about applying heavy damage from long range - normally at the cost of defence ability. You aren’t (and can’t) hide and will have to watch out for interceptors closing range and jamming your warp drive preventing escape. It’s the opposite style of combat to the brawling ship which is designed to fight at close range and soak up the damage.
So assuming you want to walk that path:
Train skills that improve range (obvious).
Train tracking skills Beam lasers, Artillery and Railguns have poor tracking and are going to be your main weapons. Tracking is how fast a weapon can slew and stay following a small or fast target. Long range weapons will slag a small ship if they can hit it. That is a very big IF.
T2 guns (the II versions with the orange tag in the icon) are a must, but a long train. They give access to advanced ammunition, one of which is a longer range punchier item).
Ships to mount it on.
Sniping only really applies to ships with large guns. That means Battleships, and the paper thin Attack Battlecruisers (such as the Oracle). Smaller ships with medium or small turrets don’t have the range in a big fight or are too easy to catch because they aren’t a long way away (20km is long range in a frigate fight, and that’s in jamming range).
And good fitting skills. Big guns take a lot of CPU and Grid to fit. And capacitor skills if you go down the Amarr route (a lot of good reasons for doing that: the Apocalypse being one).
If you want to snipe because you’ve a nasty “I like be the one screwing other people up” streak then look at e-war specialisation. You can really cripple enemy battleships with an e-war frigate. A good Crucifier can turn a devastating 100km Battleship into something that can’t hit a barn at 10km - he’s not dead, but he’s not in the fight because of you.
[I’m an e-war pilot at heart. I know what I am and I enjoy it.]
Sniping, and e-war works as part of a fleet. Solo you are going to have problems, but good range is useful for clearing missions and rats.
Reach out for me in game if you want - I’ll help where I can.