Become comfortable with a style of music and hone your skills at this style. For example, if you aspire to be a hip-hop producer, learn everything there is to know about hip-hop and practice the art of beat-making.
Build a workspace. Depending on your aspirations, this could be a full-fledged recording studio or it could be a simple computer-based setup. Always be mindful of the people you will be working with and the nature of the music you will produce. Your space must be able to accommodate all such crafts.
Create music. If you do not have a project in the works, write songs or instrumental tracks that could be used for the next one. These could be brief sketches or nearly complete songs. There will be a use for them later on, whatever their level of completion.
Meet as many like-minded artists as you can. Go out to as many performances as possible. Make yourself known. Find the people with whom you have a common ground, and collaborate with them as often as possible.
Create your own Web site. If you run a recording studio, describe your abilities and facilities. If you are primarily a songwriter or beat-maker, post some samples of your work for inquiring artists to hear.
Scour the Internet for similar artists. Reach out to them about projects that might work well. Make your skills and services known to them.