What cards do you have? Most report your balance on the statement cut date. So if you have 3 cards during the month you can charge how much you want on all of them, without going over your limit of course. Then about 5 days before the statement cut date, make sure to pay two of the cards in full before the statement date, and pay the 3rd one down to about 10% of the limit, let the statement report, then pay the remaining in full to avoid interest charges.

Of course this is only necessary if you are planning on applying for more credit within the next month or two. Even if you max out your cards and let them report one month, if you pay them down to 10% the next it is like the previous month never happened.