Website

Some people might say that having a website is not important.  I personally think that is BS.  How legitimate do you think a company is if they don’t have a website?
Can you see how a business owner might not like that? It doesn’t have to be anything too complicated or detailed.

Consider putting up a quick site using Homestead.  They include monthly hosting packages as well as a free domain so you don’t have to worry about buying a separate hosting package.  Also, you can set up a customer email account with them that is included in the package.  This might not seem to matter, but I know I instantly question the creditably of someone with a Gmail account that they are using for business purposes.  It’s because any and every one can set up a Gmail account, but when its yourname@yourwebsitename.com it instantly looks more professional.
Homestead is what I use for my websites and I have gotten a TON of compliments on them.  I’ll admit that they aren't the most elaborate sites in the world, but they get the job done and I made them myself pretty quick.
Here’s the thing with your own online presence. I not only have a website, but I created a blog and video about SEO and other services.  I’ve gotten a few of my clients who found my website and called.  It’s not very difficult (if you know SEO) to get your own site ranked against other SEO companies in the area.  Plus, it’s great to show potential customers that you were able to get your own site ranked against other people who offer this service.    
I believe that it is important to own as many properties online as possible for your business. This would include a Facebook fanpage with a customer URL, a LinkedIn account, and YouTube videos. The more that a customer can find about your company, the more legitimate you will look.