Raising Bilingual Children

This is just a question that I've been wondering about, as I've always felt kind of deprived since I was unable to learn a second language from infance where I live. So I was curious, for those who have raised bilingual/trilingual, etc... children, or who have studied on the matter, what do you believe is the best way to raise bi/trilingual children, as far as techniques, exposure, etc...

Thanks in advance!! (^^)