Brillow follow me and I'll show u the light
Really, I used to be at 15 and then Moss (Wonder if he is still around) put my noob arse on the track...
Technically speaking I have my sensitivity at 1.5 with all the default windows values, with resolution of 1121x816 or something like that.
For me to make a 180* turn would prolly take anywhere from 1.5 to 2.5 full swipes accross my pad. Thus said I have MX510 and it is very cool mouse, Swoop has crazy mouse too, but thats only cuz he is way more l337 than rest of us. (When I tried his config at FF03, his sensitivity was very very low...to the point where I could actually feel professional )
If u have some Joe Shmoe mouse then forget about low sensitivity cuz technically ur mouse will not be able to track the surface fast enough for u to make fast turns with low sensitivity.
So, to sum it all up:
1. try work ur way down gradually
2. Aim at the sensitivity of below 2
3. General idea is that u are not afraid to move ur mouse when u see an enemy
4. U need to reach the point where movement of crosshair is very slow and steady...ideal situation where u don't move ur crosshair most of the time but just keep it in the mid of the screen on the potential spot where enemey's head is going to be
5. Get high performance mouse...there is just no other way (or play like me, with keyboard only)
6. Don't be afraid to move ur hand a lot, u will get use to it.