Nine year old daughter opened a Downtown Travis Hunter for her birthday. Guidance or tips?

I know this is probably a typical post, but we are new to trading and I want to make sure I do what’s right by her in guiding her in next steps. She will want to sell for sure as I think it’s a passing fad with her as my son and I are more into it. Appreciate any input - PS my 11 year old who loves football cards is handling this well…it could’ve been his box with his birthday 5 days away….poor guy