One more tip I just remembered reading on here - especially for the younger kids: go to the open house on your first day and make sure to show your child the restrooms in the club. Walk through everything they'll need to do, as they will need to be independent and know how to get the soap, etc.
Also, for those concerned about what your child spends their club time doing, I'd recommend checking your Navigators for activities and bringing your child to the ones you/they are interested in, making sure both your child and the check-in CM know that they are going to participate in the activity. We generally did this, so I wasn't worried about DD on iPads later, as I knew she'd been engaged in an art project, etc. first. (Also, just to clarify, both times she was on an iPad at pick-up, she was playing together with 1-2 other girls on the same iPad and all the nearby ones were empty - I was happy to see them working together, not sure if CMs encouraged that or if that's just what they did, but it wasn't a solo activity for her).