quote from another thread in this forum, thought it could be useful since so many users are struggling between sniper modules and weapon and that.
i use:
weapon pro -> i tried rapid fire, but its not worth it. i tried retriever, but its bugged and always resets to 0, so its not worth it too! faster reloading (sometimes good), faster switching weapons (when you detect an enemy with prox. alarm(the thingy around your map gets red) you need sometimes to swich weapons fast!), and finally faster scoping.(will help a lot if you spot an enemy somewhere and dont want to loose him during the aiming process)
proximity alarm -> VERY GOOD for sniper, but DO NOT pay attention to the sound! look at the left corner where your minimap is. there is some thing wich is green, it fills red when an enemy is close! at level 2 you can start paying attention to that sound due to its higher warning(beeping) frequency but you should also look at your minimap, at mentioned thing.
visor enhance -> very very nice when spotting players, cloaked or not, and even behind walls!(most of them you can shoot through, and they dont expect you to do so, so it will be a nice headshot!) lv 2 isnt so important because when youre sniping and youre good at it noone will throw a flashbang at you because noone sees you as for level 3: completely uselsess! you can see enemys in nanovision only in a 10 meter radius. you dont snipe someone whos in 10 meter range, you pull your sidearm..

tips for snipers:
1. dont be a complete sniping-moving-pwning-dude and dont be a camper-sittingincorner-behindwalls-guy!
be some of both!!! example: if you kill one or two enemys move to another place. it must not be a high place or a place where the enemy would expect snipers. on some maps you can greatly snipe when you are on the ground. so move after every (or other) kill to another spot and try not to be stational.
2. if you didnt started sniping yet, use the DSG-1, not the gauss! reasons: you can mount a silencer on the DSG-1 which has NO AFFECT ON DEMAGE! the dsg-1 is an oneshot in cloak and a twoshot in normal. since it ignores armor its a twoshot too in armor mode. its demage is less then the gauss, but the gauss does more demage. its still no oneshot and it does not ignore armor!(but i think its a twoshot in armor too, due to its high demage; unless you arent facing a dude with armor enhance) and it has less mobility! and it has a slower rate of fire! so use the DSG-1!
3. if you didnt started sniping yet, your first unlock should be silencer! as mentioned, it does not reduce demage and it makes you unvisible on the map. yes, ext. magazines are tempting, but unless you do not need a full round for a single guy, you should not bother with this!
4. learn the map! there are some great spots on lighthouse, city hall, wallstreet, ... which are very nice and are not known by many players so they wont find you instantly! do experiments on empty servers and try some spots if you really want to become good.
enough tips given, try it out yourself! make sure you give me a feedback and good luck!

nice.
personally i think the DSG is more of a wuss weapon and the Gauss is a boss weapon. i've used dsg more though because of the reasons you said, but i've been experimenting with the gauss and i'm liking it. if the target has been damaged even a slight bit, the gauss take them out in one shot. very useful when your teammates are fighting in the circle and you're supporting. plus the gauss 'cause the target to enter "almost dead" mode with blood all over their screen so they'll panic, do stupid things, and it'll be an easy snipe.

The Gauss is simply cooler because it looks cool and has cool sound effects, now I'm overusing the word cool haha

The best tip is simply not to snipe

I'll give you a hint... on Wallstreet, use that BUS and some parts of building scaffolding around that building...

to madess: jes it looks cooler and has a cooler sound but its weaker and underpowered.
majstor: jeah good tips, but you should probably not tell them here, only if you want to do your own sniper-tutorial and givaway all the good things

It would be great if some newbie started pwning after reading this so I'm glad if my "secrets" can help...

On Evac Zone, try to use that hangar roof (it's highest point on the map), but be careful because you can be seen from all sides. Safest snipping place is in that HMG tower near that evac zone circle

Find most unusual place for sniping, it must have a good view, it should be hidden, , should be in some corner (so you have your back/sides safe) should have cover and runaway path...
Study the map and find few places that are great for snipping. It's recommended to change position after kills. Plan your migration from one place to another.

For sniper, it's important to be invincible, so never let your energy drains under (at least) 20% (or 40% while in sniper nest). It will fill up much faster if it doesn't drain completely to 0% (if you drain it all, you will have to wait 2 seconds more).

If you're in safe place, remain in cloak while scoping, and turn cloak off just second before shot, then cloak again.
Try to hide your body behind some wall, so others can't hit you that easy, and most important, you won't be so visible in nanovision (if you're using Blind Spot III, nevermind).
Hint for all players (not just snipers). You can be seen in nanovision even behind the cover if you're too close to cover (wall, that military cover, etc..)

If you find yourself in a dogfight 1vs1, pull out secondary weapon and try to kill the enemy with that weapon. You'll probably miss if you use sniper in close range because you don't have time to aim well (unless you're pro, or lucky, or both).
Place C4 on spots where enemies must pass if they're after you; for example, on stairs in lighthouse, or on ledges in that ruined hospital in Lighthouse. (btw: have fun with C4 in Parking Deck map... 4 ex., people just love to climb on that Truck on one side of back alley ;D)