It wasn't intentional, but the tam came out looking good on both the right and wrong sides. Decide which way you like it, or weave in ends really carefully and wear it both ways.
As written, tam fits an average woman's head. Pick a slightly bigger needle size for a larger adult head.
I worked samples in both DK and worsted yarn; both should work well, but the fabric will be drapier in DK. My recommendation would be to use wool or something with some bounce or memory to it. I think it could look nice in a silk or cotton blend, but the band stretching out would be a risk you'd have to adjust for.
Smaller needle size is used for the band only, the body of the tam is worked in larger size
I've knitted 2 versions, but the pattern hasn't been formally tested. I would be happy to hear from you for any questions/comments/errors found!