Two things here, which you are probably already aware of
1) For a donation to be deductible, that donation must be to a qualified charitable organization as defined by the IRS. Use the IRS tool at https://www.irs.gov/newsroom/taxpayers-can-use-irs-select-check-tool-before-donating-on-giving-tuesd... to make sure the organization you're donating to is a qualified charity, and that their tax exempt status has not been revoked or suspended for the tax year in which you desire to make the donation.
2) Qualified charities fall into two basic categories. Either their a 50% organization or a 30% organization. With a 50% organization only 50% of your contribution is deductible from your income. Ditto for 30% organizations too. The percentage you're allowed to claim/deduct can also be affected by your total income (AGI) as well as the actual amount donated, and a few other factors.
