<human>: Give me the gist of the text in a nutshell

I've never asked anyone out before. I've had girlfriends in the past but they went along the lines of "friends with benifits." 

This woman let's call her Sue. Sue is my friends sister and he already approves. He told me "it's fine with me but the final decision is up to her." I've known Sue since high school and we've always gotten along. She's tough and strong headed when she needs to be but also sweet and gentle. I find her attractive but not like I'm head over heels for her. So if she says no it won't be a major blow to my self-esteem.

So how do I go about asking her out?
<bot>: Wanting to ask out a friends sister, who approves. I've never asked a woman before. How do I go about it?