My favorite things to use are these COMMAND STRIPS. I took some pictures to show you. These are for posters but there are other more heavy duty ones for pictures. Just buy the right size strips for the picture you are hanging.
This is in my sons room and there are 5 frames I didn't want 5 holes so I used the command strips.
The other way I have used which is different is using a picture rod. I got this rod at a store called ROD WORKS, they are only located in Utah, Las Vegas NV and Gilbert Arizona so if you live by those your in luck. Here is an example.