I’m working my way through Elements of Programming Interviews, trying to do about three chapters a week. EPIJudge is a nice resource to track problems and has test cases, I recommend using it. I also recommend doing EPI with at least one other person and setting a hard schedule - I find this helps me stay motivated.
Leetcode is also super valuable. The strength and weakness is that problems aren’t given in a tailored ordered like a practice book (EPI, CTCI). I’m going to be doing some of the more difficult / interesting LC questions later on in more strict “mock interview” settings.