To my teenage me:
Don't be such a horrid little **** to your parents, they are fabulous people and are doing their best. Cherish them, respect them, above all be their friend. They aren't immortal.
Learn to play the piano in the front room.
Work harder at school and stop pi55ing about so much.
When John Bosley starts pushing you around, put a stop to it immediately. Otherwise he will make 18 months of your life a misery, and when you reach your fifties you will still hate his guts and want to beat him to within an inch of his life.
For god's sake talk Mark out of buying that motorbike. He will be killed on it, and it will devastate you.
To young bassist me:
Learn to read.
Yes, slap is great fun and you'll get quite good at it, but it's not the be all and end all. Work on other things too.
What you DON'T play is just as important as what you DO play.
Learn. To. Read.
You will get an opportunity to do session work in London. GRAB IT. Don't faff about indecisively.
Buy the pre-EB Stingray you will see advertised for £250.
Also, buy as many all-original vintage Fenders as you can, and keep them safe. They will be a great pension plan.
Did I say 'learn to read'?