hello hello! this is a bit hard to answer since my learning style doesn't necessarily match everyone's but here is what helps me:
Grammar
- consistently doing tasks in a workbook
- constructing and writing out sentences myself with grammar rules and vocabulary i learned

Vocabulary
- sadly, some things need to be learned by heart and the sooner i decided to accept that and make myself learn words or phrases the easier it gets!
- finding media in a language that i'm learning. for me, music actually helped me the most with any language i learned
- and same as grammar - constructing and writing my own sentences down!

When I learn by myself, I will stick to a workbook more bc it has solutions for me to check and when I take a class I actually prefer writing little essays myself where I use grammar and vocabulary and ask the teacher to check them for me!