You can buy the hack for your arcade and practice until you know how to do it. Unfortunately, there is no cheat sheet for the blue dot hack. Use this and you will never fail this hack again. For the fingerprint hack, here I have linked a cheat sheet for you at the end of this post. I realize some are just not good at hacking. You are the host, essentially the leader, it is ultimately your job to know these heists inside and out. I have found that a lot of new hosts or hosts at lower levels go into these heists unprepared to do any hacking and expect their crew to do it for them.
The number one tip I can give new hosts, or any host for that matter is, don't expect your crew to do every hack for you. Here are a few Do's and Dont's, Tips, Tricks, and general musings. As someone who just started the Diamond Casino Heists a few months ago, after being away from GTA V online a bit, I have gained some insight on the ins and outs of playing this heist from every angle.
