Thing to remember when painting is that surface prep is the most imortant factor. Needs to be completely free of dirt and grease, running some fine wet and dry abrasive paper over it, clean it again with detergent (washing up liquid, diluted, rinse, dry, then ideally use IPA (isoproyl alcohol) and a lint free cloth to give a final clean, before spraying several LIGHT coats of paint from about a foot away, leaving a few minutes between coats. Fewer coats the better. Applying varnish after will not protect the paint if it hasn't been applied correctly to start with. Preparation is key to a decent finish. Also don't mix different types of paint (acrylic with enamel for instance) or you can end up with paint finish resembling crazy paving!
