What you'll need:
1. A small bottle of paint that matches your car.
2. A fine-tipped touch up brush (hobbyist stores have these).
3. 3M Glazing & Spot putty (from most automotive stores).
4. Paper towels or a rag.
5. Excess paint and putty remover.
6. Squeegee for spreading putty (credit card will work too).
Materials costs: about $40.
Step 2: Remove putty
Step 3: Apply paint
Step 4: Done!
Should you make a mistake, the putty or paint can be removed with nail polish remover and you can try again.
Expect BETTER results on dark colors than light colors.