Keep it free of politics. This is not the time to make a statement about your religion or political affiliation. While you might support a specific group, like the NRA, some of your guests may not. The goal is for your reception to run smoothly with your guests happy, not for it to dissolve into snarky comments about the donation.
Consider friends and family who can't be with you. When trying to decide what charity to support, one method is to think about those that are no longer with us. Perhaps your uncle died of lung cancer, or your cousin from an accident with a drunk driver. Remember and honor your loved ones by supporting a related charity. If that feels too sad for your wedding day, opt to support a charity that the relative believed in. For example, maybe your cousin was a total dog lover. Choose to donate to the Humane Society in her honor. You don't need to mention to your guests that is why you selected the charity.
Offer choices to engage your guests in your causes. I recently attended a wedding that had the best idea. Each guest was given a colored token at their place setting. By the buffet there were 3 glass jars, one of each of three charities the couple wanted to support. You could choose where your "favor" went by placing your token in that jar. It's interactive and makes the guests feel involved in the giving.
Print out a nice card explaining the charity. Don't leave your guests wondering. Set out cards at the welcome table, by table numbers, or at each place setting explaining the charity you have chosen to donate to. It's also nice to give a sentence or two about what the charity does and some basic contact info for those who might be interested in learning more.
Have a thorough understanding of your charity. Weddings are full of small talk, and your charity might come up in conversation. You don't have to know the name of each member of the governing board, just make sure you know more than the name. Find out the main purpose and guiding principles of the organization so you have some extra info to share with inquiring friends and family.
Photo Credit: Zac Wolf Photography