First of all, you should check out this thread. It has some beginner reading resources that can be useful if you don’t like Yotsuba or find it too difficult. The Yotsuba book club thread will also probably be helpful.
Making your own flashcards is a big topic, and lots of people have different opinions 
. You can do entire sentences, or just individual vocab, or put vocab on one side and a context sentence on the back, etc etc. A common rule of thumb is to only have one piece of new information on each card (e.g. a sentence that only has one new word in it). But in general, yeah, you make flashcards and review them whenever the SRS tells you to, much like WaniKani. Keep in mind that you don’t need to do this right away - you can stick with WaniKani for now if you like.
Personally, I use Kitsun, but you should just try them both out and see which you like better. Kitsun has a nicer UI and some convenient features, but costs money (whereas I think Anki only costs money on iOS).