My first attempt of doing uni was four classes online. I dropped out, so I kinda have an idea of
what works and what doesn't.

I guess the main thing is to be realistic. Ever heard of SMART goals? Stands for specific, measurable, achievable, results-focused, and time- bound. I found that to be a major principle when figuring stuff out. Don't overdo it, don't take heaps of classes and attempt to keep up with them all. Give yourself time and, more importantly, time off from study. I didn't - I would wake at 9am and study through to 2am the following morning, every day. Not a good idea, I got really sick from pushing myself.

I would suggest you make a timetable and stick to it. Schedule regular breaks and downtime, and give yourself a good stopping point for when you stop for the day. Also, make your study environment comfortable but not distracting. Getting a good chair makes the world of difference - if you use some cheap uncomfortable thing, you'll be in pain and that's distracting.

Another handy thing to do is list every assignment for the semester, put them in order of due dates, and then tick them off as you go. I didn't do it in my first semester, so it was hard to complete everything on time. I did last semester, though, and ended up finishing one of them two months before it was due, because I knew it was coming and started early!

Time management is a major factor as well. Be aware of deadlines and what needs to be done. That also comes under doing a timetable, though - I set aside a specific day for assignment work and catchup work, so if there's anything left over from the other days (should probably mention that I take three classes and work on one subject per day) I can do it then without getting overly stressed and staying up late.

Um...that's about all I can think of for now. Sorry for the long rambling post, but I remember how I felt starting out so...I just wanted to help ease your fears a little. Hope I helped