There's a number of options available:
Maximizing Profit per Image
Post your photos online through a photoblog or facebook and get people viewing your images. Mention that prints are available for sale directly through you. When someone contacts you about placing an order, have them pay via Paypal and either print and mail directly or have a third party print and ship your prints. I prefer the latter option with
EZ Prints.
Maximizing Control and Presentation
Purchase an account with a company like
Smugmug or
Zenfolio. These companies will allow you to create custom websites, attractive looking designs, and custom prices for your images. The images will be hosted on their machines. You can sell both digital and print copies of your images, watermark them for protection, and have all your sales, printing, and shipping needs taken care of for you.
Read a full review of the Smugmug Pro Account.
Get a free trial and save $5 off a Smugmug account with the coupon code:
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Focusing on Passive Income
Sign up with various microstock agencies. Here you can upload your images and have customers start purchasing your images immediately. You typically make less than a dollar per image, so the name of the game is to crank out lots of high quality and well captioned images. Some sites are better than others in terms of payout, number of buyers coming in, ease of use as a photographer, how many hoops you have to jump through when it comes to uploading, categorizing, tagging, and processing images in a batch.
Shutterstock - The best option. Lots of traffic, easy uploading and tagging, and my highest paying site.
Dreamstime - My second highest paying site and still relatively easy to use.
BigStockPhoto
Fotolia
123RF
I'd also recommend using a program like
Adobe Lightroom to caption and keyword tag your images before uploading via FTP to the various sites. Not all sites use the same EXIF fields when reading data to autofill the tags and captions, but this will save you some repetitive leg work when you get to the sites to start keywording and captioning your images.
Make Money Referring Others
Finally take advantage of the various affiliate programs that the companies offer. Each of the sites I mentioned above (with the exception of EZ Prints) offers an affiliate program. For example, with Smugmug and Zenfolio, you get paid when someone signs up for an account. With Zenfolio, you get paid even when someone signs up for a trial account!
All of the microstock agencies I listed above offer affiliate programs where you get paid when the photographers you refer sell photos on the sites. In several of them you also get paid when buyers hop on and purchase photos from the various MS sites.