Take a long hard long at your playlist or music selection and notice what types of music you tend to gravitate to. Spend some time thinking about what about your current music isn't sustaining you and what you are looking for in new musical selections.
Look on sites like Rhapsody, Amazon.com and iTunes and search for your current musical selections. Look at what artists those websites and services recommend for people who also listen to your particular musical tastes. This method is often a good way to get leads on new music you might not otherwise know about.
Listen to different radio stations and write down songs and artists that catch your attention; it's a great way to get in early on a new act or artist and test the waters before committing to a whole CD. Use mp3 downloading resources like iTunes or Rhapsody to sample various musical selections. Search by genre and listen to the 30 second clips of songs to get a taste of what is out there.
Make a playlist or CD of different artists and different songs to give yourself a sampling of possible new musical selections. Spend some time with this conglomeration of new music. Notice how you respond to specific artists or songs, since it will give you a great idea of what direction to go in.