Even if you're only going in for a sniper hit, it gives you solid, fast and quiet backup, just in case something does go wrong. Also advisable is the Kevlar Vest. The rest of your weapon load depends very much on the mission you're playing. You should base your choice on the type of mission, the characteristics of the weapons, and what you're likely to face. The basic form of the weapons is this.
Handguns are small, easily concealed, and accurate at close to medium ranges.
However, you can not conceal them. The Sniper Rifles are High Velocity rifles, with magnified scope, to allow long distance hits. Most interesting here is the 'Blaser' R93, since it comes with it's own, stylish, briefcase, allowing you to carry it freely through the levels. However, it does take a few moments to set up. Finally, the Shotgun - extremely high powered at close range, but useless beyond that.