You're getting good advice. I can add that my sneak/sniper was registered with INT 4, and has max Sneak 300 and max SG 300 by level 81, along with decent Doctor, FA, and OD skill. This has been one of my all-time favorite characters to play. The ability to move into a PvP hot zone, during someone's TC operation, and run solo up to their perimeter, watch them, choose a target, switch to sniper rifle, and pick one off without being seen by anyone in their whole team, has been quite a rush. Of course, most successful crits in this scenario are knockdowns, not kills, and most hits are not crits. Plus the dmg is low compared to EW. But....they see no tracer rounds! They usually go running after me the wrong direction lol. I have to switch back into Sneak mode asap after only 1 shot to stay alive, send the rifle back to inventory (what a serious pain) and be ready to move at the same time. Tricky. If you try this, use motion sensors for sure, and carry p90 in slot 2 when running. Silent Running perk is thus a must, but Silent Death no - that's for a different plan.
Even so, solo knocking down a power armor tank thug in a TC 6-man team is worth the leveling imo. Just don't expect to be a 1-man army.
FYI: He was registered with ST 1, PE 9, EN 8, AG 9, LK 9. Planned for lots of implants though, which he now has. If i had this to do over again, i might go with IN 2, EN 10 for the extra 20 hit points, but that requires level 131 maybe, not 81. Ouch.
Also, i suggest the sneak/sniper code: stay quiet with enemies. When you lose, say nothing. When you win, say nothing. Be successful, but don't boast to your targets that it was you. Let them always wonder. Somehow for me this adds to the classiness of it all.