@Anonymous wrote:
"4. Keep balances low (1-9% util) on credit cards and other revolving credit. High outstanding debt can affect a score. All revolving accounts reporting a 0 balance results in a Fico score decrease."
Does this mean I should not PIF before my bill is due? I have a Amex Green (charge) and an Amazon Prime Store Card (credit) and I just paid the current balances off of both. Is this a bad strategy?
The intention of the writer was to say that if all of your cards (every single one of them) report $0 in a given month, then you will take a score hit. It's not a big deal if that happens. Just allow one card to report a positive balance the next month and you will gain back all the penalty points for having all-cards-at-zero.
You ask about strategy. The best answer is that there is long term strategy and short term strategy -- and they are different.
The best long term strategy is to gradually obtain three credit cards you really like (4-6 would be slightly better but only if you are certain they would be easy for you to manage). Then get in the habit of using them naturally as circumstances warrant (but only for stuff you really want or need). Let the statements print with positive balances. These balances will report to the credit bureas. Then pay them in full (PIF) in the next 25 days. You will pay no interest and will be creating a history of card use and always paying in full, which is GREAT. In the long term you don't even need to worry much about utilization, as long as you keep it somewhat under control and you always PIF.
The best short term strategy (done in the month before you need your scores to be at their best, for whatever reason) is to pay all of your cards down to $0 and keep them there -- except one. With that remaining card, let it report a smallish balance, maybe $20 or so? In the next 30 days, your FICO score will go up to about the highest it can be at that point. You only have to do this in rare situations, however, You don't have to do it every month. Only when you need to get your scores in tip top shape for some particular reason.
I just posted a summary of these ideas in another thread, including the difference between reporting and carrying and PIF. Here is is just in case you might find it helpful.
http://ficoforums.myfico.com/t5/General-Credit-Topics/Minus-13-points-for-paying-off-card/m-p/4343995#M219916
Starting Score: EQ: 721 (4/21), TU: 729 (4/27), EX: 734 (3/1) 
Greatly appreciated