I would suggest trying to stick with bursts at close range. One thing to note is that the AK spray is tough to control without practice. At short range you can use 3-5 shot bursts. Yet again, you are going to want to try to use cover or use the strafe and burst technique. At medium range, you can take the burst up to a 2-4 shot burst. This gives the AK recoil time to settle down. When using the strafing technique, you are going to want to make your strafes a bit longer than you would with the M4. It is very helpful if you are able to either use cover at long range or to strafe then burst then strafe again then burst again. When using the AK at long range, you are going to want to use 1-3 shot bursts. This weapon is somewhat accurate at long range, but most deadly at medium or close range. This, like the M4, is a very solid and versatile weapon. This is the primary weapon for the Terrorist side of matches or scrims. So you have to hit your opponent at least twice when they have a helmet. One weakness with this gun is that a headshot only does 82 damage when your opponent has a helmet. As mentioned before, the M4 is a very accurate gun at all ranges, this means that you can aim for the head and hit often. At short range you can use 3-5 shot bursts again or you can even just spray at the other team's players. One important note is that you should not try to outpick an awper from medium to long range with the M4. At medium range, you can take the burst up to a 3-5 shot burst.
When using the M4 at long range, you are going to want to use 2-3 shot bursts. This weapon if very accurate at long range, but still very lethal at close range. This is a very solid and versatile weapon. This is the primary weapon for the Counter-Terrorist side of matches or scrims.