The bad habits that got people failing out of UPT that I saw were mostly not studying enough or studying the wrong things. Stuff like memorizing the differences between front and rear cockpit of the T-6 instead of knowing boldface/ops limits or knowing how to request an instrument approach from ATC.
The thing to remember is that you need to show up prepared with general knowledge of the airplane and flying so that the instructor can spend their time helping you refine flying skills instead of reading the pubs to you.
And don’t get arrested