Everyone you meet is a potential lead when actively looking for work. Since you rely on friends and acquaintances to help you locate work, make sure you handle yourself well. This means that you develop and maintain a reputation as someone that does excellent work, is reliable, trustworthy, punctual, etc. Your friends will have a hard time recommending or asking questions on your behalf if you are not someone worthy of working with.
Volunteer. Many organizations rely on volunteers, and this can be an excellent way for you to become known in the community and expand your skills at the same time. The added benefit is that you get to give back to your community.
Do Your Research. Read the news, investigate companies, and do your homework to learn about companies that interest you or are in your area. Check their websites (and their career postings on those sites) while you develop an idea of what they are like, who their clients are, or why you would want to work for them.
When you are working the hidden job market, you are promoting yourself. Do it happily and shamelessly to get the job you want. Take advantage of publishing software to create a business card or postcard (because you won't be carrying your resume everywhere you go, but you could manage a postcard). Imagine a postcard that advertises who you are and what you can do. Make sure you aren't shrinking your entire resume onto the card; leave plenty of space.