If you work in a service role already, chances are you've got lots of skills you can offer other businesses, and all from the comfort of your own home. Small and medium-size companies often don't need/can't afford full-time in-house assistance, so they outsource it to a VA.
You might be skilled at marketing, editing, project management, typing, or planning. Once you've chosen your business area and which services you can offer clients, set up a pricing structure, create an online presence, then start pitching, networking, and building relationships to get it off the ground.