If you are an employee based in the United States, you can set up recurring contributions to charity organizations through Gusto. This makes applying tax credits each year simple as the W-2 form sent by Gusto will include your total charitable donations (Box 14 -- Other).
Charitable contributions can be made as a one-time or a recurring (per paycheck) donation. In order to set up a contribution, select Giving from the Gusto sidebar.
Then, select Choose a charity and Search for charity to open a dialog box.
It is recommended to search for a charity through Charity Navigator to find its federal Employer Identification Number (EIN). For example, the ACLU page can be found here.
Not all charities are created equal. In order to provide the most benefit for your donation, you should research how your chosen charity uses its funds, hopefully from multiple unbiased sources. Websites such as Charity Watch provide ratings of individual charities based on financial reporting factors such as overhead cost and amount spent to raise contributions.
As a cautionary example, the BLM Foundation page can be found here, but is not affiliated with the Black Lives Matter movement (the correct charity is the Black Lives Matter Global Network Foundation).