In no such order here but a strong trolling motor is definitely a valued thing to have for any fisherman. Patience better be learned in order for success to happen on a fairly regular basis. Do unto others as you'd have them do unto you, i.e, most crappie fisherman will help you all they can if you just ask. Make sure your equipment is in good working order before you head out whether you could afford expensive equipment or not it's still gotta work. More rods in the drink equal more choices for the fish to choose from, me and my partner almost always start out using different colors in hopes of finding what they want. If you carry a cell phone out there better keep a tight hold on it, i've managed to fall in with a phone on my side, let a fish splash water onto a phone and dropped a phone off the dock at a pond. To add to this I don't like to be on a phone when I'm trying to fish but emergency's happen, I use mine for navionics at times, it's great to use one for weather checks (storms) or even get the skinny on what they are biting somewhere else from a friend at the time. Never pass a fellow fisherman with boat problems up, it could be you someday! When you take kids or the wife fishing be prepared not to fish but assist. Lastly, a bad day on the water beats any old day at work.
I'm sure I have lots more to learn but these are things I've learned in my years of fishing.