Baby is seriously lacking in the pants department and has zero hats, so I made some pants to go with all the gender-neutral onesies we have, and some hats to keep his little head warm. The pants turned out better than the hats. I was able to get 2 hats and 2 pairs of pants out of a 3XL shirt I found for $3 at DI. I also used about 25 cents of elastic.
I made the pants pattern by tracing pants we bought for baby in sizes 0-3 and 3-6 months. Pants are pretty simple to make following this method, and there a a lot of tutorials for making baby pants. I found this one to be the most helpful.
I used this tutorial and pattern to make the knit fabric baby hats. The pattern is quite tiny and doesn't quite fit with the instructions - or maybe they have a different definition of "5 inches" than my measuring tape. Anyway, I enlarged it, and hopefully the hats will be useful, if not perfectly shaped. The lumpiness is due to my poor knit-sewing capabilities.