Get a boyfriend blazer

Upgrade a sleek pair of jeans with a structured blazer. For a classic look, pair a black jacket with dark denim or a bright white tuxedo design with a lighter or acid-washed pair.(Good idea for most people)

Embrace sequins

A bit of shimmer is an instant outfit upgrade. If you're a risk-taker (and your office is fashion-forward), try a bolder sequined piece.

Throw on a cardigan

Embellished sweaters lend retro charm to a pair of jeans. Look for crafty details that will dress up denim.

Buy a silk blouse

A sweet silk blouse will give your jeans a feminine feel--look for tops with pretty patterns or intricate necklines. If your workplace is more formal, skip distressed denim in favor of a crisp pair of dark-wash jeans.(This is very important)

Try a little leather jacket

A cropped leather jacket gives a jeans-and-a-T-shirt look a luxurious spin. Just skip the heavy motorcycle jackets in favor of light, soft skins in classic colors, like gray, brown or black. Add a feminine touch with accessories like a great pair of heels and a fun bag.

Look for a chic button-down

A crisp button-down shirt is a no-fail piece for the office. For a streamlined appearance, tuck a light-hued blouse into matching skinny jeans and take it to the next level with chic heels and a status bag.

Hope tips mentioned above will help you improve your dress taste.