Welcome to the game [with a long learning curve]. It's best if you figure this stuff out yourself by studying the perks, playing for hours in the online planner, read the "Hit Chance" page on wiki carefully, and come up with your own plan.
I will tell you that most PvP snipers now have Strength 1, planned for gun skill 300, hope for a ST implant, and use Buffout and maybe Psycho, wash it down with Nuka Cola. We all smoke now too. PE 9 or 10. AG 9 or 10. Luck 9 and hope for Luck implant. Do not skimp on Endurance though, even for a long-range sniper. EN 10 is standard with most fighters.
Avoid Bruiser. Do not tag Doctor since Doc 100 is good enough. Consider maybe Outdoorsman and read 10 Scout books so you can have OD 130 at level 1. And maybe First Aid (max 200) - handy even when using superstims.
You can optimize a sniper with IN as low as 2 but you have to delay some perks until the last minute and put all Skill Points into gun skill only until 180, and don't spend leftover points - let them stack up for next level.
Perks: More Crit, Even More Crit, Better Crit of course. Bonus Rate of Fire. Right Between the Eyes is a popular sniper perk but only if you plan to do mostly eye/head shots. Action Boys are good too.
Finesse has been hotly debated. I cannot offer much help on this, except to say what i hear guys say about it: don't take Finesse if you want to kill the enemy yourself. Take it if you intend to do more cripples but don't mind doing way less actual HP damage.
That is all. Build advice is tough because really, we cannot really know what you want to do without tons of questions. Maybe you want to also have high Sneak, and thus you need Silent Running and Silent Death? That's up to you. Stick around though...the longer people see you play, the more likely they will invest their time. It's a brutal world. Oh and the game is harsh too.