Great to hear!
There are two big kinds of credit accounts: revolving (typically credit cards) and installment (typically things like car loans, mortgages, student loans, personal loans).
In terms of revolving accounts, FICO really likes it when you have three or more open accounts (e.g. three credit cards) but you also keep the total amount you owe very low compared to the amount of your total credit limit. (This is called CC utilization: amount owed divided by credit limit.) The simple rule here is: all of your cards at $0 except one, which should show a small positive balance. That will get you all the scoring points you can from your revolving accounts. You don't need to do this all the time, just when you are trying to get all the extra points you can.
As far as your installment accounts go, there is a less discussed but similar principle. In the same way that for your cards you add up the credit limits on all your open cards, here you add up the total amount that your installment loans were originally for -- but only on your OPEN loans. Similarly, you then take the total amount you owe on your open loans. Amount Owed divided by Original Loan Amount also gives a %. For lack of a better phrase we'll call this "installment utilization." FICO likes it a lot when you have at least one open loan (one is fine) but your installment utilization (counting all loans together) is low: ideally 1-9%, but you will still get a fair number of points when it is higher.
You just paid off three of your installment loans, so these are now closed -- and therefore they do not not count in that "installment utilization" calculation, which considers only open installment loans.
Now that you know all this, you can probably see that the best thing to do is to continue to keep a huge loan like a mortgage open, but just pay off most of it, since it will help you keep your installment utilization low. (Obviously if it is a high interest loan, that it probably makes sense to pay it off regardless.)
Your next best step is to figure out what your current installment utilization is. (Remember, open loans only.) If you think you might be able to lower it to < 8.99%, that might help you out. We can give you some advice if you are willing to tell us what your % currently is.
A huge help for you would be to lower your CC utilization to the 1-6% area, if you have not done that yet. A long range step would be to add another credit card so that you have three. (In the short term, adding the third card will cause you to take a score hit, however.)
