My first attempt, I actually wrote individual notes for each person in my life, even online friends. Never sent them though, and they weren't found. I burned them after, cause I thought I was getting better.
I wrote a new letter recently, but it's not really a suicide note, it's kinda like a will. What I want done with my body, giving certain items away, asking them to hold onto certain items I feel are important, and giving my family permission to look through all my journals and sketchbooks. Figured those would help them understand my feelings more than anything. And a simple "I love you" at the end.