At Signal vs. Noise, Jason Fried has some advice on giving advice:

Advice, like fruit, is best when it’s fresh. But advice quickly decays, and 15 year-old advice is bound to be radioactive. Sharing a life experience is one thing (grandparents are great at this – listen to them!), but advice is another thing. Don’t give advice about things you used to know. Just because you did something a long time ago doesn’t mean you’re qualified to talk about it today.

Think you’ll get a good answer from a 30 year old telling you what it’s like to be 15? Or a 20 year old remembering what it’s like to be 5? Shit, I’m about to turn 40, and all I remember about being 25 is that I wasn’t 26. How clearly do you really remember anything from 15 years ago? And how many of those memories are actually marred by time and current experiences? How many of those things really happened the way you recall them today?

via MG