This is a wikibook that I highly recommend.
It covers information for the novice as well as the more experienced user. Here you will find advice on searching by author, chemical name, formula, and structure. It advises on how to do synthesis and reaction searches, analytical chemistry searches, property data searches,and much more.
This book is mostly the creation of a well-known chemistry librarian, Gary Wiggins, from Indiana University. He has written extensively on finding chemical information. Upon his retirement, the information was moved to wikibooks where it can continue to be updated by others.
Here are two excellent, free tools that are available for chemistry literature and chemical data searching.