I use one of those rubber finger tips. You can get them at any office supply store. I can turn pages pretty fast now but I still have some trouble turning pages with my bare fingers. I'm still a beginner.
If you are going to use something to assist your page turning, I think you should go with the rubber finger tip over the water.
With the water, you have to keep moving your finger away from the book to wet it again (which can take extra time and possibly disrupt your state). You might also stain your pages or get them too wet.
-Travis
