Number one: A good, well fitting slip will make all your clothes look better.
That slippery fabric layer lets your dresses hang smoother and move with you, rather than clinging and bunching. Have a figure-hugging dress that also hugs around your belly button and the curves you'd rather not highlight? Put on a slip. Worried about visible panty or bra lines? Put on a slip. Contrary to what you might think, adding this extra layer will actually make your clothing more flattering. It's called a foundation garment for a reason!
Number two: Tights, stockings, leggings.
If you want to wear dresses year round, at some point you'll need to wear something on your legs to keep out the cold. I'm sure we've all gotten dresses, walked confidently out into the world, and discovered that with every step your tights are encouraging your skirt to get clingy and ride up. A slip lets your skirt glide over the tights without getting caught up. No amount of Static Guard can fix this problem like a slip can.