Looking for help building an EDH deck.

I'm not sure exactly where to go for help with this. I don't have the knowledge base of older cards and I'm trying to make an EDH Angel themed deck with Avacyn as the general for a a very good friend, as she is also pretty new to Magic. Can anyone point me in the right direction of where to go? Or give me some tips on some "must have" white cards for the deck? Also, general EDH tips are welcome, as I plan to construct my own someday.

Also, forgot to mention, this deck is supposed to be casual, flavorful, and fun.