Knots & Cherries

Here's a novice stylist question: how do I get the knot to stay put and not slip out? I feel like some casual styling could be fun, but I don't know how to actually pull it off.

Refresh:

Dress: Pure + Good Gertrude Ribbed Dress

Shirt: Rails Kate Shirt

Shoes: Cole Haan Tennis Grandpro Sneakers in Gunmetal