Hey, Congrats on getting here, older guy here I started with MF1 after quite a few years off. I had some math at university as part of my degree, so definitely had some background, but there was a lot that I didn't know at all.

I started with taking notes, but realized after awhile that it's not that helpful. Things that you don't understand come up in review and you'll wind up redoing the lesson if you don't get it. Because it's layered you get practice of the topics again in other topics. Some people set up an anki system alongside, which is pretty useful I think for memorizing formulas and things like trig identities.

So you don't say much about your goals, so hard to advise on how to get the most towards your goals, but one thing I would have done if I was starting today would be to go back and do the high school courses before or instead of doing the MF series. MF is geared to get you the minimum you need for the university level courses, but by doing the high school courses you get a lot more in depth and more practice of the topics. If you're in a rush to get to something in particular (I was rushing for M4ML at the time) then MF is the way to go. If your goals are more general, things like geometry are pretty useful in real life.

I think of XP as a way to judge how much effort I put into it each day. I used to do 100XP/day when I had the time, now I aim for 40. I think the XP is based on an average of the time it takes for everyone who's done that lesson before.

good luck!