What you wear does matter, and we have all heard the saying that first impressions count. They do...and, while it is possible to overcome a negative first impression (more on that in a future post), it can be difficult.
How you dress at work can actually demonstrate your level of competence, responsibility, maturity, and even trustworthiness to some! While you want to dress in your own style, for professional events or work, it's always better to err on the side of conservatism.
Remember that details are important, too. Your shoes and socks should match and, for most workplaces/functions, accessories and ties should be down-played (nothing too 'wild'). Now, there are certainly exceptions (on both ends of the spectrum) here, depending on the field (a very creative or artistic field would provide more leeway for what constitutes 'wild', for example). Hair, make-up, and nails should be well-groomed (stick to less playful colors for things like interviews or conservative workplaces).
In any workplace or function, no visible skin should be shown (other than arms/hands and head), which includes covering legs with hose, tights, or socks. Generally, skirts should be knee-length or longer and keep the low-cut necklines for non-work functions. For more formal occasions or conservative work events, wear close-toed shoes.
Finally, remember that no smells are good smells. Both 'good' and 'bad' smells can become nauseating distractions to co-workers, whether it's a 'good' smell like a strong perfume or a scented lotion or a 'bad' smell like body odor or stale smoke. If someone can smell you before they can see you, that's not conducive to a good working environment.
Ultimately, you want to dress for the occasion. And, while many workplaces have become more casual in recent years, they have also become more inter-generational, and - at work - it is important to dress for the job you want, not just the job you have!