Easy painting books are sold at better parts and paint stores. Buy one you like, read it 4 times and then prep your car.
Some simple facts. (And I teach refinish to adjusters, and have worked around the repair industry since 1985.)
1) Do not use an orbital sander. Get a DA one, or dual action sander. The ones that just go round and round will quickly remove all your paint, and just leave you with serious scratches in the metal. (Especially if you start with 100 grit paper.)
I reccomend buying a good DA and a velcro pad. Then buy the matching velcro 3M sand paper in the following grits to remove, and prep your surface.
Remove all your trim. The moldings that come off don't have to be taped up, and it gives you a better end result. Taped off moldings generally leave nasty tape lines, and every one of them will be a point where the paint can and eventually will peel off and look like shit.
Put 3 or 4 layers of masking tape over any molding you don't remove. This will help to protect that molding from the sanding your about to do.
Wash your car. Use dish soap like Dawn, but pretty much anything that cuts grease for dishes will work fine.
Now wash it again.
Ok, with a clean dry car, no moldings, door handles, mirrors, antenna, windshield squirter nozzles and your front and rear bumpers and header panel removed, your ready to remove the rear tail lamps and the trim bezels around your head lamps. Tape over and mask up anything you do not want paint or other residue on. (Like your engine, anything under the hood, wheels, tires, exhaust and underside of the car. If you do get paint on the underside of the car, just cover it up later with rubberized undercoating and your good to go.)
Now, clean car, trim and parts removed, and any remaining parts you want to keep taped up with 3 or 4 layers of masking tape... Time to get out the DA and start with 250 grit paper. Yes this is plenty agressive paper for most prep work.
Go over the entire car's painted surfaces with the 250 on the DA. Change out paper when it becomes clogged up and is no longer cutting the surface well. Don't go down to bare metal if you can help it. I would only take it down to feather the edges of any rock chips you might have. Get a sharpie pen and mark any dents and deep scratches while your prepping the paint. You'll thank yourself later.
Now when you've gone over the entire car with 250, you'll have some areas of the factory primer showing, and you'll have marks and circles around the dings and scratches that need to be fixed up. (Assuming you have no serious body work needed.)
I like to use spot putty, or very light filler to fix most minor dings and scratches. Use a razor blade, and fill the holes, scrapes and minor door dings. If your careful, there is not much sanding needed when your done. Get a short 10" long 2x2 or 2x4 board. Wrap two pices of your 250 paper over this, and use it "board" out the spot putty when it's dry. (If you must use filler, your going to have to learn how to mix up the base and hardner, and have a pallet to mix on, spreaders to apply it with and first take the surface down to bare metal with 60 grit paper. The rough scratches help the filler to bond better with the metal. Most minor door dings filled with spot putty after sanding with 250 hold up pretty well as long as you don't try and fill more than an 1/8". (Most door dings are a few 32's deep at the most.) If you want to rough up the door dings, and fill them, just keep in mind that what you take off, you have to fill back up again...
Ok, so now your car is prepped with 250, dings and minor stuff is filled and blocked flat, and then hit with 250 over the top again. You are ready to wash the car again... (Lucky you...)
Ok, dish soap and warm water.. then repeat...
Now with dry compressed air. (If you do not have a seperator on your compressor, your just going to spray oil and crap onto your paint, so letting it dry off normally would be better here.) The compressed air is great to blow all the water out of the nooks and crannies. Watch for dirty streaks. Any dirt you leave on the car at this point will show up as nibs later.
If you want, you can sand the car with finer paper like 400 grit, but I've found most primers to be very adept at filling sanding scratches left over from 250grit paper. (Especially if you have to wet sand the primer later anyway.)
Now check your masked off areas. (like the engine, wheels tires etc.) Make sure you don't have loose paper.
Read the directions of the primer your using. The good stuff should have a base and hardner, and you will have to reduce it some to get it applied smoothly. Some primers allow you to apply the top coat inside of a "flash" time, and others do not. Read your instructions, and ask the paint supplier for the best way to apply their product. Tack rag the entire car, then mix and apply your primer. Do test spray out's first, and make sure it's going to work before you start to spray the car. Then apply a good even coat.
If you can't apply the top color inside of a flash time, your going to have to wet sand the primer after you apply it. This breaks the surface of the primer, and allows the color coat to bond with it. If your primer requires you to sand it, use 400 or 600 wet sand paper. Use lots of water, a few squirt bottles for each car. Keeping the paper wet and lubricated helps to keep it free of build up, and you have less chance of picking up a nasty chunk of debris that will scratch your paint between the paper and the surface. Listen to your paper, you can hear large nibs stuck between the panel and the paper, and it's time to STOP and clean the paper, or replace it. If you keep going, that noise is the debris putting deep scratches into your primed surface, and they will show up like you can't belive when your done.