Begin by jotting down the variables you expect to use in your welding process, consider this a "preliminary" WPS, following the variables of the "preliminary" WPS, run the required test coupon(s), if any of the variables are found to be somehow insufficient, make necessary changes, RECORD ALL ACTUAL VARIABLES USED DURING PERFORMANCE OF TEST COUPON(S), when the test coupon(s) are completed have the required mechanical tests performed, if acceptable, the ACTUAL DATA RECORDED during performance of test coupons will be used as the PQR ~ the WPS is developed from data recorded on the PQR within the range of variables provided in the applicable code.

It would be helpful to have a bit more information from you.
What code are you working with?
What do you want to have certified, a WPS to weld with? Or are you certifying a welding program?

If you only mean PQRs and WPSs , jon20013 is right in that you first choose parameters that you want to weld with. That would be a preliminary and unqualified WPS. Then you run the PQR test, which, if successful, qualifies your WPS.

Chet Guilford