Europe is a beautiful place and a big continent. you need to be specific what kind and how long a vacation are you looking for? people visiting for first time usualy prefer Switzerland or London and Paris. so, if you want you can tell me what are you looking for, I might be able to help you.
Relay mostly on cash rather than card's
keep access in more than one way to your money
avoid to exchange currency in airport they may charge you high
check your mobile is unlocked or not if not you can't use European sim
I would suggest Spain, Italy, Switzerland or Paris, France since its your first trip. Spain & Paris, France are the cheaper destinations in my experience. Italy and Switzerland are more expensive. Eastern Europe is much cheaper as compared to other parts of Europe. Prague & Budapest are my favourites in Eastern Europe.
I have been to 13 countries of europe and my travel experience is good so far.With family you can explore any country but make sure travel in summers that is june to september check out my profile for more info