My current strategy is to never do lessons if the lessons would cause the reviews in the next day to go over 50. It’s a bit slower, but that way I’ll usually get through all the reviews in a session, so I won’t forget the ones I just learned.
I also don’t do lessons too late in the day, so that I’ll get my first review that same day and have an easier time remembering it.
And listening to the vocab pronunciation every time it comes up in review seems to help a lot as well, especially when trying to remember which reading it is.
I also go a bit overboard in the notes with etymologies and mnemonics, but I think that’s just me, and it is a bit time consuming. Especially with kanji.
I tried this site a while ago, and got up to level 8 before getting too overwhelmed and stopping. I restarted at the start of the year with these techniques, and it’s been a much calmer experience getting here. Even stopping for a few months and coming back wasn’t too painful.

which is unsurprisingly not really getting them anywhere.