Sometimes it can make sense to combine the contents of the files (not the one for Internet Explorer) into a big file, which invariably leads to a large file that is not very clear.
Here are some other tips.
- Avoid redundancies in your CSS rules.
- Remove the semicolon after each final statement in a statement block.
- Combine value statements:
- Avoid too many indents and spaces.
- Remove comments if necessary.
- You can also use the free tool CSSTidy to automatically optimize your CSS file: http://csstidy.sourceforge.net/