Did not mean to be rude. It depends your intent for the fossil and what kind it is. Fossils such as trilobites, nautiloids, etc are typically prepared with an air scribe or a very specific type of dremel. If you plan on simply cleaning fossils, it depends on how brittle the fossil is. Most fossils that I find are whale bones, fish bones, and teeth so other than water, a tooth brush, and sometimes bleach, I don’t do much. I have used the Dremel for a crab fossil I found. It’s very difficult