Verify that you need permission.
Is the item available through a library database or freely posted online in a way that you can link to?
Is there another item you could use that would work as well and is available?
Find out who holds the copyright to the work you would like to use.
Check the websites listed, ask other scholars, contact your local librarian.
Decide what usage rights you want to ask for, and the period of time that you will need to have them.
View sample requests like this one for ideas.
Negotiate with the copyright holder and get permission in writing.
Keep all requests on file.