Officiating Your Best Friends Wedding!
I started officiating weddings about two years ago for a pair of my best friends. It felt super natural for me to officiate their wedding as I had known the two of them together for 10 years already. It was one of the biggest honors of my life. And I certainly learned a lot of things that first go around. I had never officiated a wedding before and I was admittedly nervous.
The bride had already set up what she wanted to do with most of the lay out portion of the wedding which I found super helpful, and a big relief too since it took a lot of the work off of me, but I still wanted to make it special.

What I realized is that by officiating their wedding, I was telling their story. Sure I was a small part of their story, but it boiled down to being about the two of them. As with most art forms, story is the key to everything.
Find something that can be applied to every bit of their relationship so it can be tied together through out the journey your taking the guests on through the history of the couple getting married. Many times guests don't know half of the couple that well so sharing those stories let the guests in on some of the "inside" jokes that the couple has, letting everyone be closer together.
A wedding is a physical action of commitment, from the couple but also from you the officiant!
At another wedding, one of my struggles was cutting myself out of the couples story, but it made a world of a difference. It drew the focus away from me and allowed me to share more about them, rather than us. I was hesitant at first, because I did participate in the travel they did, but the audience doesn't care about that, they want to know what the couple did and it's irrelevant that you were there too.
I also found that the more I cut myself out, the better it flowed. It felt more natural. Write a lot at first, and then cut away the excess fat later.