IMO, Do your research before you Try to paint anything by yourself. There are a few companies that offer automotive spray paints. Try Alsa Corps "Killer Cans" they are a can with hardener in it . If you chose to Go the Cheap Route Brands I recommend are Rustoleum and Valspar . use dish Soap and water to wipe down the hood to get the dirt and wax off . you want to Scuff your clear coat using approx 200 Grit Wet/Dry sand paper. Wipe it down again with mineral spirits or paint thinner and allow to dry. Spray a Light Coat of high build primer ( IIRC: Rustoleum brand) It will fill in the Scuff Marks. Let the paint dry several hours. Use 400-600 grit to sand the primer coat smooth .
Wash the hood down thoroughly to get the dirt and sanding dust off. Spray a several more light coats and let dry . You should not cover the old paint completely in one coat ,If so you are spraying the paint too thick . try moving the can further away or move more quickly across the hood. After those coats dry wet sand using 1000+ grit to make the surface glassy smooth as rattle cans tend to show every scratch /scuff below it. If you are OCD I recommend going all the way to 2000 grit paper in your sanding. Now to the color coat, A color coat will likely have unevenness to it if you do not have enough coats on it. Depending on the color and brand of paint you may need more or less coats. there will be over spray from the can of paint. Something I do when using aerosol paints is use a box fan to suck the air from my workspace to keep the paint cloud from settling on my painted piece.
For the bumper I would use a adhesion promoter to make the paint stick to the plastic .
I have read that you can claybar the piece to get the overspray off to make the hood smooth.
Anytime you get something professionally painted they will charge you a little more for stripping a spray painted piece.
just my 02C
Current : 2 15s 149.5@56hz 2k rms Previous Trunk box 1 18 ,146.4@43hz 3500rms,Sony 12s 145.6@63hz