It is certainly very safe to cruise around as a tourist in Sicily, the only problems you might have would be: 1. getting lost in some remote areas - in this case you should get a GPS. 2. finding English speakers - but if you're ready to grab a few basic words, Sicilians are extremely hospital and happy to show their land to tourists.

In case you want some private tour guides to some special areas: catacombs, or the Etna vulcano,... check here: 

http://www.isango.com/SearchResults.aspx?Keywords=sicily 

Cheers