When I was 15 I did my school work experience at an Architecture firm, there was an old character called Will who was a typical old bloke of the office whom offered a lot of experience and wisdom to the younger Architects and technicians. One day we got on to the subject of under aged drinking and after much discussion about the evils of alcohol he turned to me and said;
"everything in life is good in moderation, except sex, do that as much as you can"
Probably the best advice I've ever had.