I do it on the side for small companies. Setup Teamviewer, add Google Voice on your smartphone plus a separate contact email account for support inquiries. Get them some good antivirus & antispyware (like say Avast & Malwarebytes Live). I setup a lot of NUC computers for business use as well (tiny, low-power, fast with solid-state drives). If you're doing a lot of support requests, get a ticket service like Kayako:
http://www.kayako.com/
I've done freelancing at a couple points in my IT career. Last stint was about a year and a half. It's easy to find work if you don't mind visiting small businesses in person...tons of them lack any kind of IT support & love to have a geek on call rather than having to deal with a big business. It's doable if you don't mind hunting down the business!