On May 11, 2013, I wrote a post on language learning which you can find at https://latin-caribbean-travelblog.blogspot.com/2013/05/language-learning-in-class-and-on-your.html. Since that time, there are other lessons that I've acquired from experience - sometimes just observing how I react to a given situation - or reading that I've incorporated into my language learning. These are given in no particular order here.
If I feel an inner resistance to moving in a given direction, I don't struggle with it and try to force it to work. Instead, I let it go. For example, I absolutely despise flash cards because I associate them with being in school and having to memorize something to take a test. That feeling is the kiss of death for any of my language learning efforts. If I actually had to, or chose to, take a test, I would consider using flash cards, but overall, my learning is predicated on removing as much stress as possible. If you find that you like flash cards or any other method that I say that I don't like, by all means use them. Conversely, if I say that such and such a method works wonders for me and you find that you dislike it, don't force yourself.
When I write other languages or grammatical concepts of other languages in a notebook, I find that my brain absorbs the content better than when I type it on a keyboard. Certainly, there are times when typing is more convenient or has a benefit because the text can be manipulated, copied and pasted, but part of my language learning has to be done the traditional way for it to really hold.
I may resist doing further language study for a time, but I will know when I'm ready to take it on. This is a natural process that I don't rush.
If I know that I will be traveling to a place where one or several of my target languages is/are spoken, the language(s) move immediately to the front of the line before any other languages, and I practice it/ them more intensely before I go, and of course during the trip!