Step 1: Getting it all together.
-a bicycle to paint
-some basic hand tools to disassemble the bicycle (wrenches, screw drivers, ect)
-sand paper (for removing rust and scuffing the old paint up)
-razor blade (helps when removing old decals, if present)
-a piece of stiff wire to hang the bicycle up with
-primer(about 2 cans for a large bike)
-paint of desired color(again about 2 cans for a large bike and also it is a good idea to use the same brand as the primer
-clear coat if desired
-and a clean place to work, with good ventelation and a fan
Step 2: Remove all the bits
For the most part you are interested in the frame, the handlebars and goosneck(the thing that connects the handlebars to the front fork), and the seat post, for painting. If you want you can also paint some of the smaller bits like the brake calipers, you well have to take them apart so you can just paint he arms.
This is also a good time to take stock of what needs replacing, like the brake cables and handle bar grips.
Step 3: Preparing the parts for painting
After you have broken the frame down go about removing all the old decals and decorations from the bicycle, like the head badge if it has one. A razor blade comes in handy for removing the decals, either use to peel up an edge or it push comes to shove use it as a scerper. Next you well want to sand down all the rust on the frame and clean the bicycle, I use paper towel soaked in rubbing alchole and wipe every thing to remove the sanding dust and grease.
The last step before painting is to mask things off what you do not want to get paint on, like the crank bearing cups in the bottom bracket, and also the head stock bearing cups, I usally just remove these though.
Step 4: Priming the frame and other parts
Now for the fun part get out the primer. Read the directions on the back of the can, and kick on the fans if you are working in an inclosed area like me in a garage, with the door open of course. No seriouslly do it, the directions on the back of the can are there for a reason(and are often quite helpfull), and the fans are a must, paint fumes are nasty and if you start to feel sick or light headed while working stop and get some fresh air.
The best way to spray paint with cans is to, hold the can about 10 inches from the subject and to make long even passes, also it is a good idea to go and do all the junctins of the frame tudes and the bottom bracket area first, as they are the hardest to get and easiest to get runs in if you over do it. Another good idea is to use many light coats instead of one or two heavy coats.
With the primer what you are attempting to do is cover the areas where you sanded alway rust and also to fill in and even out the light gouges and imperfections in the old, worn, paint so that you have a nice ever surface to paint on.
After priming I like to lightly sand the frame, with either 220 grit wet/dry, to keep the paper from clogging, or also a red scotch brite or 00 steel wool pads, which do not seem to have the clogging issue. This gives a real nice smooth surface for the paint to adhear to.
Step 5: Paint
Sorry no pics yet, well post them soon.
Step 6: Finishing it up
If you are like me you cant wait to get it back together and ride it, but give a day or so to dry as to reduce the chances the still soft, yet dry paint well get gouged in the process of reassembling the bike.
Put the bike back together, adjust it all up and go for a ride.
In about 2 weeks or so it well be a good time to pollish, the new paint, as it well have fully hardened by then, possibly longer in colder temps. You should now have a nice new ride that did not cost a hole lot either.