Let me start by saying
NOBODY is above fashion mistakes,not even the celebrities that most people look up to! I totally agree with the guys that said what's fashionable today could be fashion mistake tomorrow.However, there are some all time fashion mistakes,they were never fashionable and they will never be.Here are a few tips to avoid falling victim:
Ladies: Take good care of your nails, chipped nail polish only brings attention to poorly groomed nails.
Choose the right undergarments. Push-up bras(the type that makes your boobs look like they are imprisoned) and overly tight
bras(especially under a tight blouse) should be avoided.Also avoid showing panty lines,if you can't wear g-strings,wear
seamless undies.
Avoid shaving off all your eyebrows, you can give it nice shape, bushy eyebrows are not so cool,especially if you are hairy
Avoid too much make-up,it makes u look like scarecrows.
Avoid too much jewelry.
Avoid ill fitting extensions, if you must use one,choose good colors,brown/blonde extensions(weave-ons)don't look
nice on very dark skinned ladies.
Gentlemen: Avoid wearing your church/office shoes on jeans(reminds me of this naija star, ogogo and his white and black shoe)
Wear trousers that are long enough to cover you socks.
Wear matching shoes and belts.
Don't pull your trousers to the chin, it makes you look funny.
Socks and sandals, was it ever right?
Ladies and Gentlemen: Buy stuff that stands the test of time.
choose colors that compliments your skin color.
Do not bleach your skin, it's yucky.
Please shave them bushy armpits before the hair gets tangled.

Don't over do trend.
Look neat and clean.
Know your body type,wear things that compliments your natural features.
Never overdose on a single fabric.
Avoid run down shoes,shoes are very very important.
Dress for the occassion.Don't wear dinner gown to church or work.
Seek second opinion.
BE CREATIVE, Do not rely too heavily on trend,you may not pull it off.
YOU CAN DICTATE THE TREND IF PEOPLE LIKE YOUR APPEARANCE!
REMEMBER: SOME PEOPLE ARE BORN WITH STYLE,OTHERS HAVE TO WORK AT IT!