If you need to use a copyrighted musical composition for a film, a performance or other project, you must obtain permission from the owner(s) of the rights and, in most cases, pay royalties. This can often be a difficult, or even nearly impossible task. But you can make it much easier, and increase your odds of success, by following some strategies that you can take are better than others.
Decide whether you actually need permission. Copyright holders are generally concerned about two things with regard to use of their music: if it generates profits and if it creates a suitable image. If you're just playing a song for a high school dance, the use is low-profile enough that permission isn't necessary. If you're using the song in a public presentation, then technically you are obliged to obtain permission. Consult an attorney, particularly if you have any uncertainty.
Determine what kind of use you wish to make of the piece in question. If you are playing a recording, then you should obtain permission for both the recording and the music itself. The former will involve contacting the recording company, while the latter will involve contacting the copyright owner. If you are going to perform a rendition from sheet music, then you need contact only the copyright holder.
Contact the copyright owner. This is often tricky, as they can be difficult to track down. The copyright owner(s) or at least the publisher will be listed on the sheet music. A published songwriter will belong to one or more of these organizations: ASCAP, BMI and SESAC. You can locate contact information for the songwriters on the websites of these organizations.
Negotiate permission and royalties. Be prepared for any sum, depending largely on the owner and the use of the song. Also, it is quite likely that you will be asked to provide a script or other information about your project, so they can ascertain that it does not violate the spirit of the music. Be prompt and thorough in providing such material.
Pay the royalty and sign an agreement, as provided by the publisher, copyright holder's representative, or your own legal counsel.
Be persistent, but not pesky, when dealing with copyright holders. Bear in mind that they may be very busy. Unless your project has a gargantuan budget, it will almost certainly be very low on their list of priorities. Try to establish a rapport with these individuals and, if possible, emphasize how your work will expose the music to a new audience, rather than just stressing the benefit to yourself.
If you are unable to secure copyright permission, or if the royalties are out of your league, consider commissioning a new piece of music that imitates or suggests the one in question. Many talented songwriters are eager for work, and you might be able to hire the services of one more affordable than you think. Alternatively, consider using a composition that is in the public domain.