If the board has been used, wash it with soap and water and let it dry before you put them on as well. I know it probably says all that on the package, but some people don't bother to read instructions.
when you say wash it with soap do you mean like regular bar soap, dish soap, etc. ?
Doesn't really matter. I don't have rubbing alcohol in the house so I just used soap. Rubbing alcohol would probably work great, too. Just make sure you clean off the grime.