About two years ago I was asking myself the same question.
I recommend from my experience that you study the forum very deeply, it is a true treasure of information. (Literally do data mining using the search option) Of course there is misinformation too but you will create an idea with everything.
You will eventually find other very similar posts with book recommendations, lineages and qigong types. (And other very good ones on the dangers and deviations of qi.)
In my little experience I recommend the same as @Rara : Zhan Zhuang, Ba Dua Jin and sitting meds. (don't underestimate ZZ try to do 1hr+ every day ).
I take this opportunity to thank everyone in the forum for the contribution they make, it has helped me a lot to obtain research points for my personal growth.