I would suggest you start by sniping properly. I never sniped before but as I got better at hardscoping, I became more and more proficient with the DSR until I can hit targets at all ranges. Quickscoping just came naturally for me but it was a by-product of getting good at hardscoping.
I now have 4,260 kills with my DSR and I think I started to get good at quickscoping somewhere around 3000 kills. MY DSR KD is now 1.69 and climbing. My goal was to get good a hardscoping/sniping properly and I didn't just go out there and start trying to quickscope from the get go.
DSR with CPU
Toughness and Scavenger
Dexterity and Tac Mask
Perk 2 Greed
Perk 3 Greed
I was in the same situation a couple months ago, and I had a terrible k/d as well. I'm now consistently playing at around 1.3-.4 when I'm looking at my weekly leaderboard stats.
Learn to dragscope first. This is the best way to get your timing down and learn to center properly. It's also the best method to use the game mechanics in your favor since aim assist only works after being fully ADSed. I only pop shot when I know I'm going to be on target or I have no other choice.
I use a 1v9 TDM vs bots at Nuketown on easy to warm up. It just getting my timing down for the upcomming matches.
Also, FFA is the gamemode I found to be very helpful when learning to center properly. This will also not put your team at a disadvantage while you learn to master this weapon.
Good luck with it, and I hope you enjoy the process as much as I have.
The class I've found that gives me the ability to be as agressive as I want is:
I can't say I've mastered qs. But I would say I just about have my snipers diamond and now I'm pretty good. Average around a 1.5 using the snipers.
I never used a sniper until this game so I was brand new to it.
My advice is start with the svu and play hardcore. Get that gun gold. Your not really going to quick scope with it. More like use it like a sniper. It should help you get your aim down.
After that practice with the dsr against bots.
The dsr doesn't get as many hit markers and seems to get kills even if your not quite 100% accurate with it
Like said above, learn how to drag scope. It really helps you learn how to get the aim down
Alot of people I see that try to qs think they have to aim on and shoot as fast as they can.. Not really the case. You don't want to black scope unless its absolutely needed or the enemy is close and dead on straight in front of you. I usually bring the scope all the way up and most of the time to get a kill have to slightly drag the scope to get a kill.
The attachments I like are CPU and laser sight.
For perks definitely toughness and dexterity.
Bringing your sensitivity up helps as well. I use 10 for the snipers compared to using 6 or 7 with all other guns.
Pretty much you use your crosshairs constantly when using the snipers.
You want to go around the map always having your crosshairs where you expect the enemy to be. So you do run around much different than you would with an smg or ar..
If you watch a few videos you could see how good players do that.
Having a higher sensitivity helps to get your crosshairs on the enemy. You don't want to ads and have to drag your scope all the way across the screen to try to follow them if they are running. Sometimes you have to aim, stop, move your crosshairs on the enemy and then ads again before you shoot.
Hope that makes sense.
So for me just recently starting, I found practicing in free for all really helped out alot. The enemies come so quick, it helps to get your aim down fast and get good at it.
And also like said above, myself i like to play a custom game against bots on nuke town to warm up.
I like doing free for all the best.
Pretty much I figured, if you can use only your sniper and beat the bots on veteran which is the hardest difficulty you should be able to join a regular game and do decent against real players.
And if you try the ballista, I find it's much easier to qs with because of the ads time, just those hit markers suck, so many times I find myself keeping the crosshairs always centered around the waist to chest of the enemy and while adsing and shooting I drag the scope to hit the enemy and also drag it up at the same time to aim slightly higher and get many more one shot kills.
I can't give you an exact time on how long it takes to master quickscoping, but it does take a while. Practicing against bots in combat training is a good idea, just make sure your technique is right. You also have to forget about your K/D because you will end up with many games where you go negative.
. . . a long time to be good at it. Being a good sniper is more than about being able to quickscope, you also need to know how to drag scope and hard scope and when to use each technique at the right time so you get the kill. Snipers have cirtain disadvatages such as a slow rate of fire which means that it is just as important to learn to play the game tactically so you don't get killed so much.
Here's some tips that might help:
1. always make sure you are in the scope before you fire, if you are not the shot will be treated as a noscope and don't try to be too quick at first, always concentrate on getting the kill with the shot as that is the most important thing, the speed will come with practice.
2. Dont move or crouch whilst quickscoping, again it will make the shot inaccurate (once you are fully in the scope moving is fine) When I started I got told to take my thumb off the movement stick when I wanted to shoot.
3. Pre aim, I use a small piece of tape with a black dot on it to mark the centre of my screen. Quick scoping is all about getting your aim dead on before you even start ads'ing, drag scoping is about correcting you aim slightly once your in the scope. A good technique to get used to this is to play a game with your average smg and do nothing but hipfire, this helps you to get used to centering your crosshairs faster.
It takes a long time to get used to and even longer to get good at, conterary to popular belief sniping is a hard playstyle that takes alot of practice. all the good youtube snipers make it look easy because they having been doing it for years. It is an amazingly fun playstyle once your used to it, just keep practicing.
and be warned. . . people hate snipers, when you start doing well with them be prepared to have half the enemy team constantly coming at you with every anti-sniper trick in the book.