If you are not friends with Fair Isaac you are doing yourself a disservice. He can be supportive in all things financial in your World. Don't be afraid of him. His goal is to direct you to a better life and he'll do so with easy to understand directions if you simply listen to the wants.
The first want is for you to pay your obligations on time and in regular fashion. The second want is for you not to over do it. Having a $20,000 credit card limit does not authorize you to safely enter into its 95% zone then realize your income cannot cover it. Ideally you should never approach even 10% of its use.
Duplicity will not increase you score either. A person with one or two major credit cards can just as easily make ends meet as someone who has twenty. When you attain 4 or 5 that should be the maximum you'll ever want or need. The lesson is to use your credit wisely and most people do not. You have to understand that credit and cash are not the same thing.
FAIR WARNING: This is George Carlin on Credits Cards
R.I.P. George (if possible!)
The biggest mistakes I see are by not letting the creditor know that you are having some difficulty. You would be surprised how much they can help you out of a sticky situation through making them aware of a problem or possible future payment problem. Waiving a couple of payments or lowering interest rates can ease you out of an embarrassing scene. Sure, you'll need to pull up on those bootstraps for a while however if you're honest with them and get your act together when you say you can your efforts can be rewarded.
Take advantage if your bank offers credit monitoring. Ask yourself can you really afford that high dollar purchase? Making a budget can be painful although it also can be a rewarding and educational experience for the whole family. Put a savings plan into action or offer an allowance to show how finances work to those younger kids. This is a lifelong journey that will see many twist and turns and it is in the preparation that keeps those bumps and hills at bay rather than turning them into chasns and mountains that block your path.
Today I had a customer call me who had not checked his credit profile recently. He knew his FICO score had been dropping slowly but shrugged it off. A simple refinance had undermined his former fine credit when the original lender failed to close the loan and kept reporting the monthly delinquencies. That loan was subsequently sold and the new servicing company continued the same reporting. Today we found that out and were able to begin the disputes. The process will take some time (30 days) but the simple act of identifying the cause was a relief. Instead of having three active mortgages totaling almost $1,000,000 dollars all agreed there is only one. Check your credit often, be cautious with its use and correct any discrepancies as soon as possible. It is good to have great credit even when you don't need it but even more so when you do!