Drew Barrymore runs a whole lot more than a stellar career in Hollywood. She’s at the helm of a burgeoning beauty empire, a production company, a wine business, and a bestselling memoir. Welcome to her next act.

Drew and I both like to say we won the sister-in-law jackpot. From the night my brother, Willie Kopelman, introduced us at a quiet dinner in Santa Monica, California, in 2011, we were add-water-N-stir insta-pals. Our wine-fueled cackles have taken us late into the night, and we’ve made breakfast for our kids with eye bags at 6 a.m. And at any time in between hours of coffee and cocktails, she is a pure joy—no prima-donna horsesh*t, no entourages, no vanity.

With last fall’s memoir, Wildflower, Barrymore has cemented herself as not just an award-winning actress, but also an accomplished writer. Not to mention entrepreneur: Her production company, Flower Films, has made more than $1 billion at the box office and released the recent How to Be Single; her makeup and eyewear line, Flower, is launching an e-commerce site this year and may expand abroad; and sommeliers across the country have added Barrymore Wines to their lists. We plopped on her bedroom carpet while our kids watched The Little Mermaid downstairs, and got to it.

On fame and celebrity friendship: “I’ve never felt comfortable with this, sort of, camaraderie of famous people. I’ve known Poo Poo [Cameron Diaz] since I was 14 years old. We just happened to know each other before her career started, and I was working in a coffeehouse trying to refigure out my life. So in a weird way, it doesn’t even count with us.”

On making an effort: “I went to parent’s night, and I wore some lipstick and concealer, and I thought the people at school looked at me kind of differently. I normally come with acne, and Ugg boots, and I thought they were like, ‘Oh that’s nice, she made a little bit of an effort.'”

On trying to do it all: “I really had to tell myself, You can do everything, but you will have to do them at different moments. And you can do a lot in the same moment, but you can’t do everything in the same moment. It was a good lesson that you will just have to prioritize and put some things over here for a little while.”

On being self-taught: “It was prompted a little bit by a fear of I don’t want to end up being 25 and not having ever educated myself in any way.”

On self-promotion: “I try really hard to keep my Instagram personal and sweet, and use it in a way to engage with people so that I can talk about work stuff, but [self promotion] is so not who I am.”

Read the full interview and see more pics in the April issue of Marie Claire, on newsstands March 22.