That boy who you're in love with? You will end up married to him. Just not for another 13 years. In the mean time, stop worry about it.
Puppy fat, aka thinking 'strawberry yoghurt slices' are healthy and and that 3 a day is good for you, will drop off once you stop eating the aforementioned strawberry yoghurt slices.
Life isn't as scary as you think it is.
But why, WHY didn't anybody bother to explain to 16-year old me that life is expensive? Why, when I decided to read History of Art at university, did no one say "You'll probably never earn much in the art world." And why, WHY didn't anybody say the same to that boy who is now my husband?
Don't cut yourself a fringe. You don't suit a fringe. Your face is too round.
Don't wear green colour-corrective moisturiser. It doesn't stop people seeing that you are blushing. It just makes you look green.
Don't worry that you're not the coolest kid at school. You can peak too soon. Where is she now? (Rehab, actually, is the answer.)
One day, you'll have a (really badly-paid) cool job that you will love.