Take care of your dental veneers in the same way as you are expected to care for your natural teeth, with the usual cycle of brushing and flossing. There may be some diet limitations, because you might have to avoid biting into hard food that can cause damage to porcelain veneers or composite bondings.
Although porcelain veneers are unlikely to stain easily, it is better to rinse your mouth with water after having tea, coffee or red wine, which are generally known to stain the teeth. The same set of rules applies for composite veneers as well.
Although composite veneers are more prone to picking up stains, the chances might still be lesser than your natural teeth. The golden rule for protecting your dental veneers will be a good oral hygiene and avoiding biting into hard food.