teabo,
To be honest, to get the best fit of your armor plates placement on your flak vest, you should get someone to help you out. keep in mind that there are curves on the armor and your body and working a 'flat' surface view isn't always goona be 'correct'.
Put on the vest, make sure it's properly fitted, then have your friend place the armor templates onto the vest and outline it with a pencil. That's how I did mine.
Hope this helps.
Stay safe,
Tim.