I like TRhit's suggestion to be yourself.
Beyond that, there is probably nothing explicit that one can do other than being inconsiderate or rude that would likely eliminate a candidate. The main thing for a recruit is to have the requisite talent and grades imho.
On the other hand, I believe there are subtle things that can leave an impression even though it may not be something the coach or group is conciously aware but these may influence their subconscience. Some things to consider:
1) Always make eye contact but not uncomfortable contact where you stare someone down. Just enough to let them know you are paying attention.
2) Of course follow the rules of etiquette when eating. Eat slow and observe the dynamics of the group. This allows you to enjoy your food and mitigate mishaps that might occur such as spills or what not. Try not to slouch over a plate or bowl but rather take your time and eat the food carefully to avoid spillage. Never talk with food in the mouth or obviously eat with your mouth open. If this is a formal dinner, learn how to use a formal napkin and how to discard silverware as appropriate such as a salad fork, knives etc.
3) Wait for the members of the group to begin eating (or other activities) before you do. This shows leadership. This shows you are thinking and are more concerned about others than merely wanting to satisfy yourself. In fact, I believe extreme politeness and consideration for others first will go along way toward establishing a connection with them and possibly demonstrate potential leadership capabilities. For example, if you were to get up to get a dessert, asking if there was anything you could get for anyone while you were up, etc.
4) I also like Orlando's suggestion above, ask questions when approriate and listen. Basically, be yourself and be friendly