If you are not a sniping type, you can stick with all-kit weapons.
But I usually, well at least before the Ghost moved into my connection, rolled with 4x scope and a bolt action sniper rifle. Just treat it as shotgun with a scope, and you can go close quarters and shoot long range when necessary.
Also, if you want to snipe, Range your shots at different location and memorize the bullet drop using the mil dots. For example, if you are using 12x scope and M24 or SV-98, in Isla first base, it is the first mil dot where the bullet would impact from attack base to defense base. Just a tad bit more if you are aiming anything beyond the sloping hills in the defense base. Reduce the mildot by half if you are using default scope.
Also, motion sensor is your team's greatest asset, and hopefully you can stick to an Assault guy who can spam you with ammo, so that you can spam those sensors.