Flats Any woman who hates, or can't wear, heels probably already has a closet full of ballerina flats -- but just in case you don't, let me tell you why they're such a great choice: they go with nearly everything. A flats that have some embellishment, sheen and or sparkle will make it appear more formal.
Sandals When it's too hot for boots, or when you need a change of pace, you'll want to turn to flat sandals. Personally, I'm partial to thong sandals because they're so foot-flattering and there are so many options, but if you don't like, or can't wear, thong sandals, then you can look for slides, gladiator sandals, or sandals with ankle straps. Finer straps, rather than chunky ones will keep your shoes dressier. Your feet need to look feminine, even if they are flat.
Boots If I could only recommend one option for women who can't or don't wear heels, it would be a classic pair of flat boots. By "classic" I mean relatively free of trendy embellishments and busy detailing -- and that's not just because they'll look dated more quickly. It's also because, even though trendy boots are fun, the number and type of outfits you can wear with them is limited.
And if you are looking for the perfect dress, do check the dresses at Pickedlooks.