To myself age... 12
1. Do your homework and deadlines, the games you play will not get any good follow ups anyway.
2. Beware of girls, they don't like it when you dump them.
3. Join the military, if you're lucky, you'll get shot. Hmm... Might have been a bit emo and harsh.
4. Stop talking to yourself, you won't like it when you start answering yourself. Oh and man up, you will be gone before you're 30. So help people out, worst that can happen you die a few years ahead, and you will miss out on some glorious years of slowly dying.