The following is a more exact process that takes longer but doesn't leave room for potential errors. The same method will be used to determine the better sensitivity at each stage, strafing while keeping your crosshair on a fixed target.
Find the sensitivity that completes a 360 moving your mouse across your mousepad from one end to the other. For me that number is 2.5, take yours and multiply it by .5 and write the number down, then take your 360 sensitivity again and multiply it by 1.5 and write that down.
It should look like this:
360 sens = 2.5
2.5 x .5 = 1.25
2.5 x 1.5 = 3.75
Low - 1.25
Average - 2.5
High - 3.75
Now perform the test, moving back and forth and determine which crosshair you are steadier with after about 5 minutes with your high and low sensitivity(mine being 1.25 and 3.75)
After determining which one is worse for you, cross it out:
if that leaves you liking the higher sensitivity
multiply it by 1.2, so for me it would be 3.75 x 1.2 = 4.5
if that leaves you liking the lower sensitivity
multiply it by .8, so for me it would be 1.25 x .8 = 1
Take your new sensitivity and add it to your 360 sensitivity and then divide by 2.
(2.5 + 4.5) / 2 = 3.5 OR (2.5 + 1) / 2 = 1.75
So now you have the following
Low - 2.5
Average - 3.5
High - 4.5
OR
Low - 1
Average - 1.75
High - 2.5
Now repeat the test using your new high and low sensitivity, cross out the worst of the two. Next instead of using 1.2 and .8 as your multiplier, change it to 1.05 and .95
So if you were testing between 2.5 and 4.5 and liked 2.5 better after that test, you would do the following:
2.5 x .95 = 2.375
So you would be left with 2.375 and 3.5, add them and divide by 2.
(2.375 + 3.5) / 2 = 2.938
So you have the following:
Low - 2.375
Average - 2.938
High - 3.5
repeat this process until finding your perfect sensitivity. After the first 5 tests I changed my multipliers from 1.2 and .8 to 1.05 and .95 allowing me to be more precise with my adjustments.