If you understand how the market works, then selling digital photos is not very difficult.
Take a look at the photos you find on stock photography sites, they are not just some snap shots from your last vacation.
These photos are high-resolution images, the one that you will later find on websites, flyers and brochures.
When you upload a photo, ask yourself who might buy the photo and for what is it usable.
Would that photo be interesting for advertising agencies, graphic artists or designer? To make profit, only upload photos that you think are usable for someone.
Because selling digital photos is only about making profit! You will have to learn to find suitable keywords and categorize your digital photos.
Think what a customer would type into a search engine (like Google or Yahoo) if they would want to find a photos like yours.
This will be your winner keyword, also if you have the chance to add more than one keyword, add 3 to 5 keywords to increase the chance that someone finds your photo.
If you are serious about selling digital photos you need to know what kind of photos are selling good on stock photography websites.
Do not waste your time on photos that are not going to make you money.
The best way to find out what is selling good and what not is to browse a few stock websites yourself.
Take notes and upload your own digital photos to make money.
The more good photos you upload the more you make.
But keep in mind, quality is in this industry the number one aspect.