Yes first fit everything up, make your lines (usually have to move fenders around a little, may have to enlongate some holes, but most ppl don't bother w/ this step, cuz the hoods usually don't fit good) - Ok, once it's all fitted up, take it off, and what color is your car? - I could really use some more info to help you better, but until you give me more info, i can help you prep it -
Take the parts and set them up so you can sand them, usually they are ok from out of the box and you can just scuff them with a red scotch pad and paint them - but go over your parts for scratches, gauges, dings n what not - fix accordingly - if it's a scratch that's not too deep, feather out making as large feather edges as possible so they cannot be noticed, this means don't run the sander or your hand in the exact same spot too long - go over a large band area -
Gauge - Do the same as before as far as you can, but you will need to fill w/ a thick primer, or maybe even means for some body filler, or you will get in the finished product what we call ass holes, and they are like feather edges that show up in the end result -
Ding - same as gauge, sand w/ deep grit (at least 100) so the filler sticks to the surface, and sand with hard block -
Well, when you are ready for paint, there is a product called HI Solve, or any paint surface prep Degreaser should work, and you must go over entire surface w/ this until it is totally free of all FINGERPRINTS!! and all greases - oils, etc... Now when you are ready to paint, you should have bought a thing called a TACK RAG, this takes all final dust off surface before painting - so there is no dirt in the paint -
This is as far as I can get you w/o knowing how you are going to paint it (on the car, off the car, just the panels, or blending into adjacent panels) whats your plan man!