Preparing fossils is a science and an art! If you go to TheFossilForum.com (sidebar link) there is a whole forum for preparing fossils. My experience is strictly trial and error by an AMATEUR! But hey, you gotta start somewhere! 😀
As I share my adventures, and mis-adventures, in prepping fossils, I will try to remember to link them here. Or check the tags and categories, because some may not warrant being posted here but may still help you.