1. Attribution, non-derivative license. Anyone can use your work and they can use it for commercial purposes; however, they must use it in it's original form. The work can't be remixed or altered without your permission. You must be given credit for the work.
2. Attribution, non-commercial, share alike license. Anyone can use your work, but must give you credit, and license their work as you did yours. You are the only one who can make money from the work. The work can be altered or remixed.
3. Attribution only. Anyone can use your work. It can be used for commercial purposes. It can be altered or remixed. It can be shared with whichever license is wanted. This is the least restrictive license.
I have been thinking mostly in terms of Creative Commons licenses of images when my students are doing searches on the internet. I want them to be able to find the real source of an image (not Google) and attribute it properly. Now, I am also wondering about the benefits to students of licensing their own images. Aside from the philosophical benefit of contributing to open educational resources and keeping money out of the hands of the internediaries, students might be able to Google themselves and find out that their name has been credited to an image somewhere. Someone might contact them to see if they could use an image for a commercial purpose. I had not considered this from the perspective of the student creator before.