How close can you get to your credit limit before it negatively affects your score?

My friend told half, but that doesn't seem right. (ie: credit limit $500...you can only use $250)|||Anything over 10% of the credit line causes a score to drop. Your friend is wrong and you are right.|||30% is standard.... 10% is the wise thing to do and at 50% you will see your score start going south.|||ideal is only 1% to 30% useage