One way to make Ringtones of your favorite songs is to extract the part of a song as MP3 using Audacity. I haven’t put a detailed explanation as how to extract a part of a song as MP3, may be some time soon I will.
Coming back, Audacity way:
1> You should be an experienced user, ie, should have hands on experience using Audacity,
2> You need to have Audacity downloaded and installed on your computer.
There is another easy solution to make your own favorite ringtones, for free, online.
Make own Ringtones, with the help of : http://makeownringtone.com/ a free online ringtone makes is extremely user-friendly with a simple interface. It varies from other online ringtone makers in the fact that it provides several methods to turn your ringtone into a unique one.
Hope you enjoy this find.