Sanding and Primering

Can anyone help me with this? I just bought a bodykit and the stores want me to pay an arm and a leg for sanding installation and primer.

Can anyone give me som tip for sanding my bodykit, is there a certain way im supposed to do it and i have duplicolor sandable primer, is that alright for primering my bodykit after its sanded?

Please help me it woul be much appreciated:(

i would say sand it. prime it again then sand it again then take it and get it painted.

what type of primer should i use for it?????