One of the ways I save a ton of money is this great method I started when my son was quite small. He was always in the same size as his age. If he was 4 he was in 4t. That is at least after the 1st year, he was smaller than his size then and it took a while to catch up. But after that it was pretty predicatable. This was especially the case with his shirts. So I do not normally buy for the current size or season. As soon as it hits Feburary I will begin to shop for his clothes for next winter. I will buy a size 9 or 10 since he is currently wearing an 8. I am able to buy many of his clothes that way. I do not normally shop at thirft stores for him because I am able to get his clothes even cheaper brand new. Last year I found Rebox Addidas and Nike hoddies for $4-6. I ask the sales person to leave the hanger on and I stick them in the back of the closet till it is time for him to wear them. I like this way of doing it. The only problem is that I cannot find jeans this way. I look but very rarley find them on sale. The other problem is that if I buy them used the knees are gone in like a week. I hate to see him wear them after that. So this works mainly for the shirts and when he was younger it worked for outfits. I have no idea if this will work for you but I love it and it has suited us well.
I also often update my clothes this way, but I just don't need as many. I wish it worked for my husband and to some degree it does, but with his job he wears t-shirts all year around so I am always buying them. I just thought I would share one of our frugal ideas.
I hope you are having a Merry CHRISTmas