In general, Macintosh users will have to be more restrictive than usual in naming files and directories. DOS and Windows (pre 95) can be less restrictive.

Avoid spaces
Macintosh users like spaces. UNIX machines and URLs do not. Avoid them. In fact, Fetch, a Macintosh file-transfer program, automatically converts spaces to underscores when transferring files to UNIX machines.
Avoid special symbols
Don't use & _ # or other odd symbols in your file or directory names.
Avoid redundancy
Don't repeat portions of directory names in the names of files and sub directories.
Keep names short and descriptive
Give your files and sub directories short but descriptive names. Remember, these names appear in your URL. Also, keeping your names short simplifies your URLs.
Use lowercase characters only
Unless you have a compelling reason to do otherwise, strictly use lowercase characters in file and directory names. Remember, URLs are case sensitive.
Give file names meaningful extensions
File name extensions are three or more characters that follow the file name and are separated from the file name by a period. Extensions convey information about the contents of a file and help Web browsers know how to display or serve a document. For example:

index.html - An HTML file.
graphic.gif - A graphic file in GIF format.
newsletter.pdf - A newsletter in PDF format.
movie.mpeg - A video in MPEG format.

Use these extension conventions for files that you create. Note that translation programs such at RTFtoHTML automatically append a .html to HTML files that it creates.

Name your primary HTML file index.html
If the primary file in your home directory is called index.html, you need not specify it in URLs. For example, both of these links work, but the shorter one is more conventional and might be easier for others to remember and for you to type:
Okay:http://www.kennesaw.edu/student/index.html
Better:http://www.kennesaw.edu/student/

Create an index.html for every sub directory you create
In general, each sub directory you create should have an index.html file. Exceptions to this rule might be a graphics sub directory in which you store graphics files and a forms sub directory in which you store comments forms.