I thought I'd share this with you because it's something I found out accidentally and is so incredibly easy to do. Have a look at the effect I achieved on this plain Royal blue tissue paper:
Ignore the fact that I've covered the paper in Tulle.
Its just water. One single quick spray, left to dry and this is what turned out. I did try it on some pastel coloured tissue paper, nothing happened, so I think it's down to the type of dye used or the depth of colour.
I used to use this technique when painting with watercolours. The only reason I found out how to do it on tissue paper was because I accidentally dropped some water on said paper. Having witnessed the resulting blob, I decided to see what would occur with a quick spray and voila!
I would think one could do exactly the same for creating texture on Crepe paper.