I would only take a course or two at once online, see how it goes, how you like it and respond to it. I would get a printer if you don't have one so you can print out the syllabus and lectures, etc. and really study them and mark them up, etc. I got a degree online and some of the organization was hard for me because everything was online and I felt more comfortable printing some things out so I could "see" them and get a sense of their organization. With everything "there" at once it can be easy to panic at the amount so I kept reminding myself that I only had to do "this" lesson or this project, not worry about the final project or what I had to know or read in the next month or two.

Experiment and find your own rhythm for doing the work in front of you. Participate a lot in the online classroom work and chatter as that will keep you interested (like here) and writing stuff out, questions to others or clarifications, etc. will teach you the material and get you familiar with it.