How delightful to be asked! It will be different for every woman, but communication is the key. I'm with Alexxx on this one - mix it up a bit until you find what she likes - she'll tell you, using words or otherwise. Also, you can get too much of a good thing - if you keep mixing it up, you won't overstimulate her or get annoying - variety is the spice of life! But I think the key is not being afraid to ask.
