I've been lucky enough in most of my jobs to pretty much wear what I want. If you have to wear a suit every day to work this probably seems like a dream but it's easy to get quite lazy and find yourself in jeans and Converse most days. There's nothing necessarily wrong with that of course but what you wear and how you present yourself at work does make a difference in terms of how people respond to you. After showcasing a few new outfits at work one week, I knew I was making a different impression when a colleague of mine commented 'have you had a re-brand?'. If you're feeling like you want to be taken more seriously at work, or maybe there's a promotion you're looking towards, then a good place to start is how you're presenting yourself. This doesn't mean you have to lose all individuality and become a corporate clone. Nor does it mean that what's on the outside is more important than who you are on the inside.
But if you're wanting to be perceived differently, it can mean that the un-ironed shirt or the tights with the small hole that hopefully no-one will notice, might just not cut it anymore.
Think about what people are seeing when you walk in a room. What sort of impression are you making? Slightly dishevelled and unsure or confident and together?