Music You Like
It might sound obvious but looking through your collection is a good starting place and one of the best ways to communicate your personality through your routine. I'm sure after having a root through your collection you'll find a few pieces, which you can check the bpm of (see guide) or at least a theme that you can use to search for music at the right bpm.
Movie and Film Soundtracks
There are a plethora of film soundtracks readily available. Most are exceptionally well recorded and produced plus, because there's such a range of them, you are sure to be able to find something to fit the styles of your routine and horse.
Tip: There are so many soundtracks to choose from so think about the mood and theme that you want to portray with your routine and whether any films have similarly themed scenes that you can use the music from.
Danny Elfman
Talking of film soundtracks; Danny Elfman is one of the most prolific composers in the business and seems have a midas touch for movie score.
Yoshida Brothers
The Yoshida brothers are a high-octane Japanese-style instrumental band. Instrumental music is great for dressage routines, particularly that with a strong beat.
Cafe del Mar
Some slower tracks are useful, particularly for walking sections of your routine. Cafe del Mar is exceptionally well put together chillout music.
Vitamin String Quartet
Popular music with recognisable hooks and themes sound great when put to dressage but are sometime held back by overly dominant vocals. Groups like the Vitamin String Quartet provide a perfect solution with instrumental versions of popular songs and artists arranged for strings.
Dance Music Compilations
Largely instrumental tracks are preferable for dressage routines and dance music compilations are a gold mine when looking for rhythmic, modern music and mostly instrumental music. Try brands like Ministry of Sound, Gatecrasher, and other club-style collections.
Adverts (Commercials)
Modern adverts often use popular music. A lot of thought goes into the placement and they're usually well themed so keep your ears open when you're next watching the box!
The Watchmen Soundtrack
I recently went to see the Watchmen film; the music was exceptional. It has lot's of texture and dynamics that can be edited to reflect the flow of your routine.
Compilations
Compilation CD's like the 'Best of' an artist or genre are great because they provide a collection of songs that fit well together but each have their own character. This is exactly what you are looking for in a dressage routine - music in each section should be different enough that the sections are clear but not so different that it sounds disjointed and badly themed. The 'Now That's What I Call Music' compilations and others like them are a good way to make sure you're up to date with what's going on in the charts.
Classical Music
Most of the ideas on this page have been about modern/popular music but it's certainly worth mentioning that classical music has rich pickings. There is such a wealth of material out there so you're bound to be able to find something suitable. There are some brilliant modern remixes of classical pieces too if you want that contemporary edge.
Musicals
The music from musicals is a good choice for freestyle dressage because it ticks so many boxes; it's popular and recognisable i.e. engaging, there's usually a range of moods for each of your sections and the music was written to sit together well so no issues with disjointed routines.
Music Inspired By
As well as the traditional soundtracks, many films have "music inspired by the film" collections. These collections are another source for tunes with enough differences to outline your sections well but have been chosen to fit together.
Norah Jones
The music of Norah Jones has a strong sense of rhythm/beat without being overbearing. It will also link well to country, jazz or other popular female singers.