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!