Bobby Pins, is there a correct way to wear them?

I received an email from Folica today.

Did you know there's a correct way to wear them?  Nope, neither did I.

One thing they pointed out that is that  The side with the grooves is meant to be against your head. This helps the pin collect more hair and lock in place better.  I never knew that, did you?  I always put the groovy side up.

A second suggestion is not to just use water to hold the hair down, but to use hairspray or texturizing spray on the hair first, and then putting the bobby pin in your hair.  The hairspray can help lock your hair in place and sort of keep that bobby pin stuck in your hair.

Other suggestions were securing a second pin across the first for double security, and getting rid of bobby pins that have lost the rubber tips because it damages your hair.  And from personal experience, you can poke your head with the sharp point and cause bleeding.

Do you have any suggestions on best practices for bobby pins?