New tax law limits your deduction for real estate and state and local income taxes to $10,000. If you have little to zero balance remaining on your mortgage, and your medical expenses do not exceed the threshold for deductibility, then the next $16,600 ($26,600 - $10,000) of charitable deductions will provide you with no tax benefit.
The standard deduction is now $24,000 plus $1,300 for each spouse over 65 filing a joint return. Alternatively, you can make your charitable contributions directly from your Required Minimum Distribution from your IRA. This effectively allows you to fully deduct your charitable contributions in addition to taking the full standard deduction. Multiply this additional deduction times your tax bracket and you have a very nice savings. You must contribute directly to the charity from your IRA with no donor benefit — not even a small token. The amounts for someone filing as single or head of household will differ, but the concept is the same.