Firstly, you must make it your mission to use the AK74 all the time. Do not snipe, do not change sprayer, make that your only gun for at least a month.
Train everyday, practice shooting at a Window at close range, medium range, and far range. Practice fully automatic shooting, burst shooting (2-4 bullet bursts), and single firing. Practice all of these whilst standing up, and practice all of these whilst crouched.
I recommend burst firing almost all the time, 3-5 bullet bursts should do it and you should be killing people in your first burst or second.
The most important thing is you become familiar with your spray pattern and find the gamestyle that suits you most. The AK74 is more than capable of killing people fast from any range you just need to play smart and focus on improving your aim.
Do not k jump all the time and do not k jump whilst shooting. Either use the regular jump or just walk with your weapon if you must move and shoot.
I'd have to agree with this, but just to clarify, make sure that when you use a weapon, you don't over do it and make sure that you don't treat it like a JOB because you'll begin to hate it and it makes things much more frustrating. Have fun with your weapon as much as you can and be OPEN MINDED TO ANYTHING.
Also, one thing I learned with AK/M4 is that if my bullets are spraying all over the place, 10/10 times it will be because I am controlling the recoil TOO MUCH.
Always keep that in mind. Proper positioning and bursting and blah blah, you can do all that and still have your bullets fly everywhere. Even if you think you aren't controlling it too much, you are.
Once I got that part, I was able to check myself and correct mistakes. Before I used to go into trainings and shoot walls and sometimes fraps myself playing and then watch to try and figure out just WTF. Although I don't do that anymore really, it still may be a good idea for others to check mistakes and see what you can improve on.