best friends brother

I feel like this is all I ask about! My best friends brother is finally single, and I still have a huge crush on him. This is like the longest I've held a crush lol. He has liked a ton of my Instagram pics, watches all of my insta stories, so I know he must at least think I'm cute lol. I know there's chemistry, too. But I'm still nervous to tell him how I feel. Usually when I'm around him I'm with his sister and the rest of their family, but I spend the night there often. I guess I just don't know how to get him alone so I can tell him! I'm definitely going to wait a little bit to make some more progress with subtle flirting, but when the time comes, I need ideas!!!