One cannot deduct the value of time or services when he or she works as an unpaid volunteer, but can deduct cost of buying and cleaning uniform if the uniform is unsuitable for normal wear. For example nurse who is volunteering for local charity can deduct cost of buying and cleaning uniform. But if charity is asking for black bottom and white top-this is not deductible, because this type of clothes is suitable for normal wear.
If you make goods and donating them, you cannot deduct their value, only what it cost to make them. For example, if one makes cookies, deductible are only cost of cookies ingredients. If you are donating used clothes, value is calculated at 25% of the original cost, and of course you can deduct full price if your items brand new, but not more than original price paid.
If value of donated property is overstated, IRS may assess the 20% or 40% penalty on the underpayment of the tax.