Invest skill points into dropsuit command and profile dampeners. Personally, I won't be too concerned with armor or shields as a scout because you should be avoiding head to head gun fights. Even with more armor and shields, you won't survive a fight with your sniper and side arm with a heavy and probably even an assault if they've seen you first. Take the long way around, decrease your chances of running into anyone else, and save your sp on things that matter like light weapon sharpshooter (which increases your maximum effective range), light weapon capacity (increases your total ammo, but not clip size), and the sniper skill itself to decrease scope sway, which is eliminated all together after a few seconds when crouched.

Putting cover on one side of you and a hill to your back is a good choice for setting up shop. Keep an eye on an objective and an eye on "high traffic areas". Call out movement if you've got a mic and UVT, warn team mates of incoming hostiles (especially those of the HAV variety), and warn your team mates about other snipers even before you take a shot at them just in case you miss. Tell us if you kill them. I'd rather assume they're still there instead of run between objectives and get downed while hiding on apparently the wrong side of what looks like a shipping container. Intel doesn't get you WP, but it makes you a better team asset. Remember: you're the guy up in the hills with the binoculars. Most of the others won't be.

Oh, and putting a few skill points into a different weapon is fine. Please do have a back up plan.