The first consideration is the color of the house and whether the garage door is exposed to sunlight or not. Whenever you decide to paint garage doors, you must think about the color of your house and the garage door paint colors will largely depend on that.
If your house is of bright color you may use some color which will match with other exteriors of the house or you may decide to go for a contrast selection. If the garage door is exposed to sun rays during the day then you may not go for a bright color as bright colors tend to fade away very quickly in sun and the door will require very frequent repainting.
For selecting the type of paint that should be applied, in cases when you are repainting garage doors, it is important to know the type of paint which is already there on the doors. If you have oil based paint, you can apply latex paint or oil based paint but if you have latex paint then you can apply only latex paint over it. In case when you cannot confirm the type of paint which is already there, it is advisable to opt for the best quality latex paint for repainting the garage doors.
Once the type of paint and color is decided the question that arises is how to paint garage doors. You can very easily assign the task to professionals but if you love to do it yourself you will find that it is a very easy and tireless job.