What helped me was picking a book in some random subject you're interested in, and translating it into your mother tongue. I'm translating some books by a Zen priest who only writes in German into English. I start by just copying (I mean, manually typing out into Logseq or vim) a sentence in German, then I make a stab at a translation. Then I fire it into deepl, and then I combine my first attempt with the machine translated one.

After the first 50 pages of this (I did a page a day) I stopped needing deepl so much and just now use a dictionary for words. My spoken German was always better than my English, and now the problems I have are pronunciation instead of missing words or poor sentence structure.

YMMV, but this worked for me :}