The first - and possibly most important - step is to select the appropriate database for your topic. There are many different kinds of databases out there, but you're looking for an index-type resource, that covers the literature of a field across all publishers and formats. There are many to choose from across all subjects. Here are the most useful ones for chemistry:
SciFinder (Chemical Abstracts) is a comprehensive tool covering the chemical literature back to 1907, and is used primarily by researchers and advanced students. The search interface is not particularly intuitive or user-friendly. The search algorithm doesn't work like others you may be used to. Retrieval on simple searches may be overwhelming, since CAS indexes thousands of publications and millions of patents in over 50 languages. Caveat: You have to register for a personal account in SciFinder and log in before searching.
Requires users to register with a utexas.edu email account.
GS is a popular free search engine. It indexes the full text of millions of articles in electronic scholarly journals across many disciplines. While the search interface is simple, there's not much you can do with it other than enter some words and then browse voluminous results. It's fine if you just want to find a handful of relevant articles quickly. But you shouldn't rely on Google Scholar for comprehensive searching, especially in chemistry. GS is also completely unvetted -- it indexes junk alongside good stuff and makes no distinction.
