I took a look at your website online, to get a better idea of your niche. Based on what I see there, I'd recommend the following:
First, some basic stuff:
1. Social networking is important of course. People look for recommendations from others, and local social reporting sites such as Yelp.com have gone wild over the last several months. Video blogging is a big thing these days, and even short videos are perfect. It doesn't have to be something overly professional...people want to connect with the real you, so be who you are and do what you do. Let them see that and it will build your brand and crediibility with your target market.
2. Don't be afraid to ask for recommendations and retweets/likes/+1, etc for your business. People like raving about someone they trust and have had a good experience with...we're just usually so busy we don't make the time to do it unless it is put in front of us!
3. Be involved and engaged in the online and offline communities that match your niche. Follow along and post regularly on blogs or forums that relate to what you do, and include a link back to your site or most recent blog posts. Attend local events related to your niche and see about leaving creatively done flyers in local coffeehouses, hangouts, etc that match up with what you do.
Related specifically to your niche...
1. You could do video blogging on various topics such as a "behind the scenes" of an audio mix. Show them the equipment, your studio, how you go about making various types of mixes, etc. Show various before/after versions of a bad mix versus how you fix it up or would have done it better (be careful of any copyright violations, of course). Don't worry about giving away "insider tips". Most people wouldn't steal your ideas, and the rest of your audience will love seeing the "man behind the curtain" and that you're a real individual with personality. And being willing to give away quality information for free builds respect and credibility.
2. Offer free mini-mixes or snippets of what you can do as downloads. Showcase various styles and such to highlight your varied skills, and to draw interest from a wider crowd.
3. If you are interested in blogging (and I see you have one), it doesn't have to be a daily thing. You can post a couple times a week, on industry-specific topics (news, artists, equipment developments, political issues, etc). You can generate a crowd of followers by offering a giveaway of some value, and allowing multiple entries based on various tasks they perform (leaving a comment on the blog, reposting about your giveaway on their blog and linking back (builds your credibility in search engines), "liking" you on Facebook, "tweeting" you on Twitter, +1 you on Google, signing up for your RSS feed, etc.) There are random generators that can pick a winner for you. And then mention your giveaway on every industry-related blog or forum that will allow it. Contact blog owners directly and offer them a semi-customized pre-done post with a link back to your site, so they don't have to do any work and already get a post for their own blog for free. And make sure you mix up the length of your posts, the content, etc.
4. Don't ignore offline marketing, or tying it into your online efforts. Consider creating flyers that include QR codes which you can post anywhere there is a bulletin board...college campuses, grocery stores, coffeshops, local dives, etc. The QR code can link back to a sample of your work, a special coupon code for subscribers, etc.
5. Make sure you maintain a database of some form with all your clients in it, and potential clients who simply contact you for information. Email or call them periodically to see if they have any new projects they need help on, or to offer them a coupon code off their next mix with you when they refer a friend who successfully completes a job with you.
6. Consider offering some kind of referral commission to anyone who sends you a paying client. It could be as little as 10%, or any number that makes sense for your budget/profit ratios. But it can net you free (possibly global) advertising, especially if you approach people in a position of authority in your niche and offer them an easy way to make some quick cash by just sending out an email or putting up a post.
Just a few suggestions. Hopefully it helps get your own creative juices flowing!