The trick to a sporty look without looking like you've stopped trying, is to start simple and then add unexpected textures or pieces.
I start with a baseball cap and then I go one of 3 ways...
#1 - Sports Luxe
Sports luxe makes the most sense, so it's somewhat easier to style. Go for clean cuts, modern fabrics, and androgynous pieces. Throw in one or two ultra-feminine pieces to balance it out, especially if you have short hair like mine! A solid color pencil skirt and heels are the perfect pairing with a baseball cap.
#2 - Vintage
If you prefer a more retro look, pair your hat with classic, lightweight fabrics like chambray, searsucker, or other cottons textiles. Denim works, too. This can take the whole look a in tomboy direction that's perfect for warm weather.
#3 - Off Duty
Goofy face? Check.
If you're channeling off-duty, Cara Delevingne is a great inspiration. She's always wearing hats and irreverant expressions.