A mini-van has other connotations... if this van is rocking don't come knocking.

So if my 16 year old daughter (hypothetical at this point) had a date with a 16 year old boy who rocked up in a minivan I would interrogate the little tyke until he turned atheist.

Lunch or Dinner and a movie or something fun, ice skating or some such. Leave the beach for later unless you already have gone to the beach with her.

Be clean, smell nice and don't worry. Be yourself... just a shiny clean version.