These are 4 main principles for effective study or learning:

S - spacing

T - testing

I - interleaving

C - categori...

• Active recall what you've learned or simply test yourself.

testing yourself 1 is much better than rereading multiple times.

• The more you test yourself the more you remember

1. You SHOULD test yourself even before you learned some topic
2. Test yourself before, during and after learning the specific topic

• Leave the space between your topics
• You probably would forget something
• But after you retrieve it, you'll remember it even more than if you don't forget

1. If you want to learn somethiniyg, you should put a structure and categories for information, than just learning
2. It's about building a tree of knowledge
3. Tree of knowledge is helps you understand the subject better

• Mix the problems of what you want to learn
• It will struggle more (it should be hards and pain in the ass)
• But it will be more easier and effective in the result