A eulogy is a speech given at a memorial service in memory of the deceased. One need not be a great writer or orator to write and deliver a great eulogy. The best eulogies are heart-felt depictions of the loved one, full of stories and, yes, humor.
Decide on the tone. How serious or lighthearted do you want the eulogy to be? A good eulogy need not be uniformly somber, just appropriate. Some eulogy-writers take a serious approach, others are bold enough to add humor. Used cautiously, humor can help convey the personality of the deceased and illustrate some of his/her endearing qualities.
Consider the audience. Write the eulogy with the deceased's family and loved ones in mind. Dwell on the positive, but be honest. If the person was difficult or inordinately negative, avoid talking about that or allude to it gently, as in "He had his demons, which were a constant battle."
Be Specific. Avoid reciting a list of qualities. Instead, mention a quality and then illustrate it with a story. It is the stories that bring the person--and that quality--to life.
Be concise and well-organized. Outline the eulogy before you start writing. Brainstorm all the possible areas (personality traits, interests, biographical info) to talk about and write them down. When you're ready to write, cover each area in a logical order. Give the eulogy a beginning, middle, and end. Avoid rambling or, conversely, speaking down to people.
Rehearse. Read the draft of your eulogy aloud. If you have time and the inclination, read it to someone as practice. Words sound differently when read aloud than on paper. If you have inserted humor, get feedback from someone about its appropriateness and effectiveness. Remember, writing is 90% rewriting, so expect to revise your work several times before it shines.
Relax. Before you speak, calm yourself by realizing everyone in attendance is there to support you. It may help to have a glass of water with you on the podium to help you maintain your composure. Just know that everyone will appreciate your efforts and admire you for having written and given a eulogy. You can't fail.
Use a conversational tone. Talk or read your eulogy to the audience as if you are talking to friends. Make eye contact. Pause. Go slowly if you want. Connect with your audience and share the moment with them; after all, you're not an entertainer, you're one of them.