Restoring an old bike is a fun project and gives you a great sense of accomplishment when you finish your bicycle restore. The one step that should require the most time is the painting of your frame. Since there are a lot of steps involved and it cannot be completed at time it requires a lot of patience.
The first step to re-painting your old bike frame is stripping it from any old decals, paint, rust, or anything else that has built up over the years. If your frame has glue from decals or other substances that are not coming off you may want to try a product called Gu Gone. It removes glue and gunk with ease. Once you remove all dirt, glue, and gunk from your frame you need to begin sanding. I would recommend using 220 grit sand paper to keep from scratching your frame too much. You will need to remove all the paint but it is OK to keep some of the old primer on the frame. When sanding, be sure to wear a mask to keep you from breathing in any of the paint dust. If you bike is old enough the paint may contain toxins.
After your frame is stripped you will need to primer it. You can buy auto primer from your local auto store. Take a rope, string or shoe lace and put it through the neck of your frame and use that to tie it to a tree or fence. You will want to primer and paint outside or in a well ventilated area. Make sure you are away from cars or houses and pain downwind to prevent primer or paint from flying back onto you. From about 2-3 feet away begin spraying your primer evenly onto your frame. Let it dry by following the drying time on the primer can. If the primer can recommend to sand then follow the instructions, if not then do not sand. If you do sand and go through the primer you should redo that portion.
Now that your frame is primered you can begin painting. You can find auto spray paint at your local auto store. Be sure your frame is clean of dust and dirt. Use the same method and style painting as you did with the primer and do not over paint. If you over paint or get too close you will begin form drips on your frame and once they dry you will need to sand them off and re-paint. After your first layer you should do a light sanding, after the drying period is over, and clean your frame free from dust and dirt. You are ready for your second layer. Follow the same method as before. If you want, you can add a third layer but it is not always necessary.
Once your paint is done you need to add a clear enamel coat. You can buy this at your local auto store as well. Apply it using the same method as the paint and primer. Follow the instructions on the can and once you complete this step you are done.
Your bike will look brand new and you will have a great feeling of accomplishment.