Numbing Creams

Hi Guys, I have heard of people using numbing creams such as Dr Numb and Emla. Do these creams actually work? and what is best? I have tattoos and never used the creams because i believe if you want a tattoo you should experiance the thing. But my fiancee wants a tattoo and loves them but is terrified of needles and is scared she wont be able to handle it to get the piece finished. Thanks.