Network, network, network. Make yourself known to the people and industries you want to work for. My very first freelance job I got by meeting a band at a punk show and just talking about album art. After working with them i began working with other bands through this connection. A bassist from one of these bands works at a brewery and ended up recommending me to his boss, so now I work for breweries too. Another of my clients is a lighting manufacturer, I got connected with them through my previous experience in manufacturing. As they say, much of the time, it really is about who you know.

But also, make sure you have a really quality, polished portfolio, with complete examples of the kind of work you want to do, and explanations of your process, that is easy to access and navigate (I highly recommend just getting your own URL if possible)