What you already know and your motivation for searching the patent literature will guide your work:
- By number. With a patent number or patent application number, finding the document should be not too hard. It should be just a matter of finding a database with the right content and matching the required format. Searching Espacenet is a good option. Doing a regular Google search with the title or patent number is another good way to search.
- Keyword searching is appropriate for exploratory work that can be less than comprehensive or as a strategic approach to classification searching. Google Patents is a good place to do that.