I HATE when people tell me "do what you want!". I prefer people to come in, show me something I've done and say, "I really like the way you did that. I want to get a blah blab blah on my [whatever area]. I was thinking of maybe adding some [whatever]. What are your thoughts?" More often than not, if someone tells me to do what I want, and I draw something big, they get really upset because they didn't want that much coverage, or they didn't want that type of flower or whatever.
I'll show someone a drawing. If they want some minor changes, ok, but I won't do several drawings. If they are coming to me, and they like my work, and they've shown me something they like, then they should be happy with the drawing (especially if they tell me I have artistic freedom).
I once had a client who had a badly done lower back tattoo by someone else. She told me how unhappy she was with it. She also told me that when she went to the original artist, she told him, "do what you want!". He did what he wanted. It wasn't what she wanted. She came to me to get it covered. I asked what she wanted, and she said, "I don't know, do what you want! Make it look nice!" I told her to go home and think about what she wanted, because I didn't want to do something on her that she wouldn't be happy with because it wasn't what SHE wanted, and then she'd be seeing some other artist saying that I did a bad job and her tattoo wasn't what she wanted.
Different situations may be different, but I feel that a client needs to have a pretty good idea first.