Some things to say in a funeral eulogy include discussing the person's background, your relationship with him and any milestones the person achieved. Additionally, include information about what the person's legacy is and what made him special.
If there were any significant periods of time in the deceased's life that help to shape him into the man he was, talk about them. For example, if the person overcame an obstacle with great success, talk about the characteristics he had that made him able to do that. Consider giving a brief run down of the person's accomplishments or milestones. Include information such as when and where he graduated from college, his wedding, his job, or the birth of his children. Pay tribute to the times in his life that were important to him and his loved ones.
Discuss how your relationship with the deceased affected you or guided you down a particular path. This also ties into what the person's legacy is. If he was a beacon in his community, a charitable person or a loving father, elucidate on those things for those in attendance. Be as specific as possible, discussing what made the person special. For example, if he was a doctor, discuss what breakthrough he made or mention a few patients he helped.