Professional swimmers, and those with the physique of a pro swimmer, are the only ones allowed to wear a speedo.
If your underwear covers more than your swimsuit, find a new swimsuit.
Popped collars are in no way cool. Neither is wearing more eye/lip liner than your girlfriend.
If your tan makes you look like A) an Oompa Loompa or B) a beaten leather jacket then you should stop tanning and stay indoors for a while. Maybe even see a doctor.
The bra is a tricky thing to dictate.
Sometimes you can't wear a top without risking bra straps showing, but if you know the strap may show, wear a bra in the same color as the shirt.
If you are wearing a shirt that your bra will show through, either wear an undershirt or wear a bra that is the same color as your shirt. White shirt with a black bra is tacky.
Unless you don't have any boobs to speak of, wear a bra. If you are very well endowed, opt for a corset instead of a strapless bra.
Don't go for a run or any sort of exercise without wearing a sports bra, they exist for a reason.
Low cut shirts are okay. Shirts with a neck line down to the belly button are not.
Lycra is a no. Just no.
Neon Colors, unless for safety, are under the label 'Do Not Wear'.
Belts are meant to keep your pants up. If you are wearing a belt then your pants should not be down low enough to show your underwear.
Dress for the weather. If it is snowing, then you shouldn't be wearing a mini skirt.
If you choose to wear high heels, wear heels that you will be comfortable in and learn to walk properly in them. In high heels you are supposed to walk on the balls of you feet, not placing all of your weight on your heels. If you know you can't wear 4" heels without being sore in an hour, then don't freaking wear them!
If your shirt's arm holes are wide enough you can see your entire side, buy a new shirt.
Dress appropriately for the occasion. Somber colors for Funerals, dress clothes for Weddings and formal events, etc.
Perfume, Cologne and scented body sprays are to add a slight nice scent, not alert everyone within 50ft. of your presence.