Unless it blends in with your skin tone, brown shoes match more loose-fitting, casual dresses. They are not ideal to wear with a formal or blue cocktail dress. I love brown shoes with a blue-dress-office-look, myself!
Red is a classic color and works wonderfully with blue outfits, particularly blue dresses. It gives the look a nautical feel, so I love it for summer and outdoor events.
More flirty than red, it's the perfect color shoe to wear with a casual or fancy blue dress. If you want to be more subtle, baby pink heels will look pretty too.