You could try the very unusual approach of...
Just be yourself. What do you guys normally talk about? Just start with that.
Then just tell it to her like it is. You have something on your mind, or youve been meaning to talk to her about something...
Stop delaying asking her, by thinking up questions to post on here, that you already know the answers to!
Youre good friends, you know her far better then we do, go for it!
Youll be fine sweetie!
Let us know how it goes!