How do you use duolingo?
I'm still figuring out the best way for me to learn with duolingo. At the moment I'm trying not moving on to the next new section until I get a streak in the timed practice, to make sure that I know what I've learned so far really thoroughly first.
It'd be interesting to hear what others are doing though :)
When I was your level, I was trying to progress through the tree as fast as I could. When it becomes obvious that you need to slow down, then slow down.
Duolingo adjusts the content of your lessons based on your performance, so I would depend on Duolingo providing the review. When your tree's golden color starts to fade, then, spend time on review.
You learn the words by trying. If you get the answer wrong, then Duolingo will give you the right answer. Check that and learn the words. How do you get words in the vocabulary? Every time you get a word right, it goes to your vocabulary. Then to get it all gold, you need to practice. Hope that helps.