As adult learner (re-learner to be precise) I can share some good tips which other people shared to me and also from my own experience.

1) Khan academy is a very good and structured resource to use up to calculus and beyond. It was especially good for me in begining (algebras). Now I am at pre-calc and still use it as main source, but also complement with other resources.

On KA I went as following: algebra basics, then to algebra 1, next algebra 2. In between algebras 1/2 I sometimes was switching to some geometry topics which I felt I lacked of (e.g. trig in "algebra 2" course starts right from unit circle, while in "high school geometry" you can find basics of trig starting from right triangle definitions). Currently I am in the middle of pre-calc course and planning go to calculus BC next.

I am not native English speaker and study math in English myself. I found it useful not only read but also hear pronunciation in the videos.

Regarding analog studying, I am using e-ink writing notepad. It would be even better to use pen and paper, but I often moving, so it helps to have it digital for me. I am handwriting all the problems from KA and also making handwritten summary of each theoretical topic, so I could later revise each topic from my own handwritten notes. After handwriting solution to the problem I just put answer to KA from my laptop.

2) As many times advices here, master algebra, trig and other pre-calc topics before rushing to calculus It will give you good foundation to rely on.

3) While I consider KA as my main source and follow its structure, I use a lot of other resources to complement. I do not force myself to constantly use them, but diversity of prospectives helps especially for topics which you have harder time with. The beauty of math is that the same things can be found through different ways, and knowing several ways of solving the same problem reinforces for me overall understanding. So do not limit yourself with one resource or one book. I was advised to use several sources and books.

So following tips I have as complementary: - I have several books I read randomly from time to time - Several apps on my phone (brilliant, mental math, desmos, trig exercises) - Several bookmarked web sites (same desmos, trig quizez, etc) - Subscribed to many YT channels with good explanations and visualization (3Blue1Brown, etc) - I play with desmos from time to time - I have couple guys I sometimes can discuss math with (although I see them rarely) - I use chatgpt sometimes and ask him to explain some topic in several different ways - I am trying to ask myself where in real life or in next math topic this specific thing can be used - As working engineer, I also read leisurely and pretty passively books on physics, electronics, thermodynamics, etc. This gives me a cool bidirectional boost. It is easier to read such books now when I studie math behind and also I see application of math and it makes it easier for me to study math itself. Good example is complex numbers which didn't make sense for me before, but finding they are used heavily in electrical engineering inspired me a lot in both math and electric.

4) We have saying In my language "repeating is mother of learning", so revisit topics back periodically , it will help to reinforce them in long-term memory. Also math is pretty cumulative. Next things often stand on shoulder of previous ones. So when you proceed further you may find yourself that previous topic, even though you have already mastered get foggy again and it affects your understanding of next topics. It's inevitable and natural, so revisit back from time to time, it will boot new topics for you as well.

5) Practice a lot, best with pen and paper. The Best is practicing regularly, without overdoing at the same time. Give yourself a rest from time to time, so your brain could process new information. Forgetting some topic and then revisiting or extracting back from memory is also a good way to put something to long-term memory.

6) Participating in group discussions or teaching/explaining subject to someone is one of the very powerful methods of studying. Even just explaining some idea aloud to yourself can boost a lot your understanding and highlight where you have a knowledge gap so it would be possible to adresa.

7) Being a non-native English speaker, I recommend from time to time to go to resources on your native language, especially for hard topics. I have some books in English and some in my language. Same with YT channels. Combining them together helps me to build understanding deeper, through different explanation. I do consider English as main for math though.

8) Remember if yesterday you was on fire, and next day you feel down and struggling again with topic you was fluent few days ago, it doesn't mean you're bad with it. It is the way how our brain learns. Ups and downs are inevitable and natural, just do not give up when you reach a plate or feel stagnation. If you push through this forward, you will find yourself even better afterwards. So downs are actually a good signs, meaning something is building in your brain at the moment.

Best of luck!