How do I ask my bestie out on a date?

This girl and I are close friends like besties so it feels awkward for her to show too much affection towards me but she and I are both physically attracted to each other. Iv tried asking her out before but something always comes up but Everytime I ask her if she wants to hang out she would agree if she wasn't busy on that day. I'm doing this lately my crush has been acting nicer and more affectionate around me lately. Her face lights up when she sees me. Then when she walked away when I saw her yesterday, she looked back and smiled at me then waved bye. Recently Iv started kissing her on the cheek more often when I see her but yestey when I saw her morning time she just woke up so she was wearing a really reavealing tanktop that show alot and some short shorts that girls sleep in. For some reason I was really getting turned on more and I was mostly staring at her eyes and lips mostly. When I went in for the hug I was kind tilted my head towards the corner of her lips because I don't think she would like me to kiss her but I wanted to show kiss her on the corner of her mouth to show I want to be more than just friends. When I tried to kiss her she moved her head so she would let me kiss her on the cheek if this makes sense. I want to spend time with her as much as I can but I don't know where to take her. Everytime I ask her if she wants me to buy her coffee and take her out to lunch she says aww and she would smile but she says she won't have time because she has to go to work. So I guess in a way we have a very flirty friendship with each other