The cost and upkeep of work clothes and uniforms are only deductible if you are required to wear the clothing as a condition of your employment, and the clothes are not suitable for everyday wear. As one actress recently learned, you need to be able to show the items were not suitable for everyday wear. (Apparently stating you obviously incurred the expenses in playing a character with unique style and pointing out that the amount you owe is small isn't enough support. See the Roth CPA Blog for a more in-depth post on the Tax Court decision.) Your choice not to wear the items outside of work doesn't necessarily make them "not suitable" for everyday wear. I choose not to wear suits for everyday wear, that doesn't mean it isn't suitable (no pun intended).
So who gets to use this deduction? Typically the uniforms of firefighters, law enforcement officers, health care workers, and mail carriers are "not suitable" for everyday wear. Theatrical performers can typically deduct costs of costumes and accessories that are not suitable for everyday wear. Additionally most protective clothing (hard hats, work gloves, safety boots, safety glasses) are deductible for those required to wear the safety items. Some of the examples seem logical, for example you don't typically see a police officer walking around in uniform or an artist in full costume if they aren't working). But, also remember these must be un-reimbursed expenses. If your employer purchase the clothing, you cannot deduct it.
Practically speaking, not many individuals can use the un-reimbursed clothing expense deduction. If your clothing expenses do qualify, in addition to providing receipts, be prepared to prove the apparel is not suitable for everyday wear.