Mom365 put together a great article about how to look better on those days when all you want to do is stay home in your pajamas: 10 Comfy Ways to Look Put Together. You don't have to be a mom though to get some good tips.
My favorite ones were: "Go Fitted" - wearing baggy shirts just makes you look bigger, it doesn't really hide much. "Rock Some Layers" - I wear layers a lot, and a black tank top underneath can do a lot to cover up and make you look longer while being discreet. "Cover Up With A Cute Coat" - who doesn't love covering a little extra tummy with a cute jacket or coat! "Pick Dark Denim" - Dark clothes hide the bulges better, which is why almost everyone looks good in black.