After December 25, keep your eyes open for deals. Most of them will be unadvertised. You just have to be on the lookout. Some of the best ones happen in January, too. I expect there to be a target sale in the middle of January, and a big borders toy sale, too. Watch the clearance racks. Some of the clothing stores are already advertising that they are getting rid of this seasons stock to get the next seasons in. Macy's often has a $5 rack. Know your prices so you know what is a deal. Don't just buy something because they are advertising it as a mark down. I often will stock up on classic things when I see them on clearance. You can always wear black or jeans. If you don't change sizes much, then this could be a good time to by pieces for cold weather. If you do or your little ones do, you could be stuck buying things that wont fit down the road. Also, we haven't had most of our cold weather yet, so if you haven't got a coat yet you should find them for cheap pretty soon.
My rule of thumb is any clothing item under $5 for adults is a good price, under $2-$3 is a good price for kids. Toys have to be 75% off or more. Clearance paper goods at 90% off. I am willing to get nonesense if it is under $1.