Dear 16 Year Old Holly -
I am not sure what I can tell you that you don't already (think) you know. You are the second oldest but the oldest in the house right now.
Stop and take it all in. There is so much going on right now and you don't have the best memory - so take as many pictures as you can. And write who is in them on the back - you forget names easily.
Don't waste your money trying to fit in with the cool crowd. Abercrombie & Fitch just isn't you. Stick with those plaid pants you wear all the time. They are awesome. People will still like you for you - not for what you wear.
Spend as much time with your friends. When you go to college everyone's lives get a little busier. Talk to them as much as possible. Visit them. They will always stay your friends - your best friends.
Enjoy all the sports you play and the people you play them with. You will look back on those days and wish that you were still playing (and wish you had that much energy).
Spend more time with your family. Once you move away it doesn't come as often as you would like.
Don't worry too much about boys. Boys will come. You will meet plenty of boys in college. The second boy you date is the one you will marry. He is perfect.
Speaking of husbands, you will start a family and instantly know in your heart that that is what you were put on this earth to do.
Trust yourself. You know yourself best.