I revisited the first post and there is no mention of what type of photography you plan on doing. Clients could be portraits, but could also be event or architecture as there is a client you would deal with.
We have a website, we have a Facebook page to promote to other businesses that have Facebook pages that will also promote us.
For pet photography we have volunteered at a local humane society with great results as they use our photos with a watermark and provide a link with each post. With each adoption we give a personal use release and printing instructions. This helps with more than just pet photography as pets are part of the family, possible new clients. Giving back to the community is also great for opening opportunities, the second day after the Humane Society posted a few animal pictures we gained a wedding in the fall.
When we shoot events, they will post a link to our gallery of photos on their FB event page sending us all the participants from the event.
If your city/town/village has a framing store or gallery, choose locations around town that people are familiar with and produce photos that are different than all the others and they will sell, the frame stores here are more than happy to display work for a small percentage of the sale. This is where you have to understand what people want and how to produce it. Doing this I sold usage rights of a photo to the Visitors Bureau for their fall brochures, which led to a contract for the next year shooting our four seasons and events, which lead to a local foundation and their events, etc.
Something we've setup to try within the next month, is to setup in a very popular salon for a day for glamour type shots in a workshop type atmosphere at a discounted rate, be sure market ahead of time, possibly even displaying samples of your work to build interest. This will help your work in front of others and get the salon ahead of their competition.
Get your lighting figured out, creating photographs is capturing light. After studying light for quite some time and practicing, my work greatly improved overnight with the purchase of better lighting. More detail, higher quality and much less work in post processing. Your work must stand out in a crowd, over time you will develop a style but keep it consistent (even though it will mature), I just made sure my style was different than anyone locally. Practice, Practice, Practice... it took 2 years for my style to develop.