When I purchased my car in 2016, I financed $16k+ for 5 years at the usual interest rate. In order to afford having a car, my plan was to pay off the $265/month payments ASAP, which I did in 25 payments. Later, my rent was increased and I obtained a personal loan from my bank at low interest to pay off all debt. That payment is $244/month now, but I have 1.5 years remaining. My CS is 808.
I agree with the paying off your statement every month. I was told that as long as you wait to pay off until your statement actually drops/ processes, then your payments will count towards being a "credit worthy" person vs if you pay off your debt in the middle of a statement cycle and there is a zero balance that processes from your credit card company. In my eyes, the point is to show that you have debt that you can afford it ie pay it off. I never quite understood where the "carry over a balance" comes from...
I also have a few lines of credit lines open, a medical CC, store CC, and a "regular" CC for my day to day expenses. I've heard the same advice you gave... don't have too many open lines but have a few and keep them active. Sometimes closing a line of credit will hurt your score but only because it messes with whatever ratio they look at. My personal opinion would be to close the line if fraud was an issue any maybe reopen another but I'm not sure how that would affect your score ??
I've been following a few of the tips that you listed and I have also have a good credit score! Kudos to us, hopefully others will follow and it'll help them out as well 🙂