Very soon after I began playing in a string quartet, during the early 1990s, I started making arrangements. You could say that it was my "gateway drug" to composing. A wedding request came in today for the Schubert Serenade, and when I realized that the arrangement I had in hand (the one I made back in 1995) was really not something I thought would sound very good, I decided to revise it. Rather than making my re-arrangement from the arrangement I made (below), I started from scratch and used the original vocal score.
I was 36 in 1995. I was an adult. I had a degree from Juilliard, and I had a lot of professional playing experience (at least as a flutist and a recorder player) to my credit, but clearly I had no idea how to make an arrangement for string quartet. I plowed ahead anyway, and after 16 years of playing in a string quartet and writing for string quartet, I'm kind of proud to say that now, looking at the arrangement I made today, I have made some progress.
Here's a link to the whole score and a set of parts.