Tip: Licensing your photos

As a general rule you should always retain the copyright to your photos then license use of those photographs to other entities. This way you can 'sell' them again and again.
Beware, some photographic competitions make you give up your copyright as a condition of entry. This would mean you wouldn't be able to use that photo elsewhere without their permission.
PhotoCritic has an excellent guide on this topic...

Read about it at PhotoCritic