Attention!: This is a basic guide for the way I spray paint my model cars however it should work just as well for anything else. I suggest trying this out on a test peice first to see the end result.
If you wish to add/correct anything pm me and I'll add it.

There are many different types of spray painting, the most common is the canned stuff you can buy at your local hardware store.
(Sorry, but I dont have any actual pictures because I dont have a camera.)

I usually start by sanding the area just a bit to give the primer something to catch on so it wont end up peeling off. You really dont need to sand the object too much, just a bit to make the surface feel a bit rough.

Then after Im done sanding I wash the area off with a little bit of soap and water, make sure you rinse all the soap off, this is to get off all the dust and other stuff that can ruin a paint job. I then dry the object im going to paint with a clean rag.

After its dry you can start with the primer, shake it well and try a test peice first,
When you believe your ready start, lay the object you wish to paint on a flat surface in a well ventilated area then start painting from the outside and go in.

Now this is where most people screw up, only give an area 1 coat of primer/paint then let it dry and then do another coat, most people who have never spray painted or have little experience tend to go over a spot they missed, this is a big no no.

After letting it dry your ready to start laying down the actual paint, do the same as before and start outside and go in, only do 1 coat at a time then let it dry and then do another coat till you get what you want.