Facebook these days is way more than just a "Social Network Platform"! Having a business presence here is important, keeping it updated even more so. I suggest posting an image or an ad once a week.
Your business Facebook page needs to be optimized with images, logo and business details, Keeping it professional. Give some background about you and the business, show off pictures of your work.
A Facebook business page is an important tool in helping you create a portfolio of your projects and list of services provided.
How does Facebook business work?
What is a Facebook business page? How do I advertise my business using Facebook?
Use your current friends list to promote your business for free. Use Facebook ads to get your business in-front of targeted, prospective clients. Once you have your business page set up there are ways to boost circulation without paying, share a post at popular times and keep it interesting.
I would be happy to set you up with a Facebook business page and get you up to speed with making posts, targeted advertising and promotions.