The first step in finding and winning public art commissions is to get on as many competition notification lists as possible. The AFTA Field Directory lists hundreds of public art agency web sites. Many, but not all, have places where you can sign up for announcements whenever there is a call for artists. Some of them have artist registries where you can submit your work for invitational calls. You should apply to as many of those as possible.

At the minimum, be sure to sign up for these announcement lists, some of which are new since my book was published.
4Culture
Las Vegas Arts Commission
Urban Arts Institute
California Public Arts Association (CALPAA)
Call for Entry (CAFE)

Art Opportunities Monthly This costs $20 per year for a monthly PDF but it's a reliable source for public art competition announcements plus many other opportunities such as exhibits and residencies.

For a more complete "look inside" and more places to buy The Artist's Guide to Public Art"

A listserve for artists and others interested in sharing ideas, advocacy and mutual support.

With 25 years of experience, Joel Straus Consulting (JSC) provides highly customized art planning, procurement, management, and appraisal services to corporations, hotels, foundations, municipalities, and private collections nationwide. We specialize in developing and implementing art programs that expertly integrate art into interiors, landscape, and urban design. Drawing from an extensive network of artists and galleries worldwide, we create extraordinary regional, national, and international collections. Our unique approach to projects combines creativity and efficiency. We make innovative artistic choices while effectively meeting each client's financial and developmental goals. Additionally, Joel Straus has completed Uniform Standards of Professional Appraisal Practice (USPAP) and International Appraisal Association’s Core Course in Appraisal Studies.