Those seeking skill based tips on how to play as a sniper would best be referred to CloaknDagger's Sniping tips reproduced below:
Before the actual tips, let's discuss construction of your HOUND. You always want to have at least three sniper cannons linked per shot. This can be accomplished with deadly accuracy at maximum range by using the best stability chip (Baukus - 5 slots), and by properly testing the firing order of your cannons in the Trial Sortie. Different order of fire will have wildly different results at maximum range, so test thoroughly until you have a tight group at 1000+ range.
With six sniper cannons, you can have two sets of three, and use weapons group #3 with two sniper cannons, one each from slots #1 and #2. With this setup, you can fire group #3 first (2 shots), then switch to group #1 (2 shots), then group #2 (2 shots). This strategy is used to hit a strafing target at a distance.
As a general rule, you always want to travel above 150 speed, so you can avoid DD volleys at a distance, and move to hills and other vantage points quickly. this narrows your choices down to a few specific legs. I prefer the RJ-Naqa legs (Sal Kar chicken ones) as they have the second-best stability of all and will grant you 165+ speed.
Cloak's top 13 tips countdown:
13) Sniping at a distance can seem cumbersome with apparent lag and fidgety movement from your opponents. A great way to hit a lagging distant opponent is to treat him like he wasn't lagging in the first place. Don't shoot into the lagged HOUND, shoot like you would normally: In front of him. Take your best estimate to where he would be in a few seconds if he wasn't lagging, and take the shot. You'll be surprised how many times you nail him right where you wanted to.
12) Average human reaction time is one full second. If you have six sniper cannons in two sets of three, and your target is unaware of you and holding still, you can hit him with all six. Fire the first volley, then immediately fire the second volley. If done correctly, both volleys will still be in the air before the first one hits. Once the first one hits, the second one is only a half a second behind, far too quick for a surprised enemy to see, let alone dodge.
11) Two seconds. That's the average amount of time it takes for the best CE rounds to travel it's maximum range. When you're leading a moving target across the map, shoot two seconds in front of him.
10) The larger the legs are on an enemy, the greater the priority that target becomes. First, you can reliably hit them from further away. Second, they have higher durability, so you want to soften them up. Third, large legs are slower, so when you shoot them out their disadvantage is compounded. Always remember that damage transfers directly from legs to the 'pit when blown out. In order: Treads, Heavy Morskoj Reverse Bipeds, Medium Tarakian Reverse Bipeds, then everything else.
9) Concerning Quads - Don't worry about their legs. Instead, concentrate on their clustered weapons/'pit area for a quicker kill. Their legs will never carry them anywhere close to you.
8) Learn to run backwards and snipe. Creating distance between you and an incoming enemy means the difference between killing and dying. Never forget to run backwards when being chased down.
7) It's OK to give up the hill advantage. Don't be afraid to allow an aggressor the top of your hill if it means you can create distance. For instance, if you're on top of a hill sniping into a target, and he turns his attention to you, be prepared to allow him your hill. Drill as many shots as you can into him, but once he starts ascending the base of your hill to get to you, start backing out. Once he gets to the top, you should be at the bottom on the other side, running backwards at full speed while keeping a constant crosshair on him. Stubbornly staying atop your hill will only allow your opponent to close the distance and kill you.
6) Creating distance - There are two major ways to do this. The most common way, which I urge you to prioritize, is taking out your opponents legs. Most soldiers run at speeds between 160-200. With your own 150+ speed, taking out their legs means you will be able to create an infinite amount of distance between you and your target to get a comfortable shot. 2-3 well-placed volleys will cripple most legs, and from there you can create distance and set up the killing blow. The second best way to create distance is by letting your opponent fire. Against cannons especially, to continue to threaten you, they have to constantly keep firing. Run backwards at full speed, and turn only to dodge volleys. As long as they keep firing, you keep creating distance. Don't stop to fire your own shot until you're at a comfortable gap, ans always aim for their legs first.
5) Sniping dodgers is easier than you think. Most people dodge in an "S" pattern. Right, left, right, left. The trick to hitting them is anticipating a turn inwards. Once the target veers left, keep your aim slightly to his right. Once you see him begin to turn right again, fire. He will walk right into your volley. A great benefit to fighting an "S dodger" is that you can create infinite distance while he is dodging. While you're running backwards in a straight line, he is swerving right and left, losing ground each time. Create enough distance this way, and he might stop dodging all together. This is when you can plant a key shot in his legs and ensure an easy kill.
4) You are a tree. At least, that's what you should look like to someone scanning the horizon. After planting a volley into the side of an enemy from 750+ meters away, HOLD STILL. Nothing is more comical than watching the guy you just gutted spin frantically from right to left trying to decipher movement on the horizon. If you move, you blow valuable cover. It doesn't matter if you're bright pink and shaped like a boulder, it is almost impossible to see a still target at a distance. Use this to your advantage. If you absolutely have to move, wait for your target's head to turn.
3) The Pause is your best friend. You know the one I'm talking about. When that Double-Double or cannon mech fires, he holds still for a critical two seconds. Funny thing is, that's the time it takes for you to make a shot from maximum range. Anticipate the shot on your target... really anticipate it. Right when you see the flash of his guns, bull the trigger. Doesn't matter how much they're lagging at 1000 meters, you're still going to hit him.
2) It's inevitable, you're going to end up in a close-quarters fight eventually. here's how to maximize your chances of survival. Always use your mini-camera in the top corner to aim. While zoomed out, you rotate at a much faster rate than you would if you were zoomed in. this will allow you to keep up with the movements of close targets. Your goal in this situation is the same as every other situation: Shoot the legs to create distance. Against cannon hounds, never, ever fire first. Wait for The Pause from his shot, dodge, and fire. If you commit to a shot first, you pause for your opponent instead of him pausing for you. Again, wait for him to commit to a shot, then fire your own, right at his legs. If you survive long enough to take out his legs, create distance and finish him off. He will try frantically to sneak in that last cannon shot when he knows he's stuck. Just stay calm, dodge his shots, and realize that you can take your time to create enough distance for the killing blow.
And, Cloak's #1 sniping tip!
1) Always aim for a Double-Double's cannons. Always. The golden rule in Chrome Hounds is that damage transfers. When you see a Double-Double pause for a shot, shoot everything you have at his cannons. 2-3 volleys will take it out, and the Golden Rule means his cannon has now become a huge 'pit. Suddenly, that Double-Double isn't so menacing with half the shots and a huge "hit me" sign on his gun. In fact, I love this tactic so much, I usually take out both cannons, just to neuter him completely. If this happens, he basically counts as dead, and you can ignore him altogether.
This announcement has been brought to you by CloaknDagger. Remember, to snipe like a pro, snipe like CloaknDagger! He's always watching you!
My apologies for quoting so many people, but as previously stated, I haven't much experience with the sniping field and have just begun my recent journey towards sniper valor. I hope this helps and obviously, should anyone have anything else that they feel would be pertinent, please feel free to add it.