There are three basic elements to a Font tag: Size, Color, and Face. For example:
will change the face of the text to look like this
will make your text one size larger
will make your text one size smaller
will change the color of your text
These tricks are helpful for highlighting specific points of interest beyond simply CAPITALIZING them, making them <STRONG>strong</STRONG>> or <EM> italicized </EM>.
Most computers will recognize three basic fonts: Helvetica, Roman and Arial. The latest versions of Netscape and Explorer will be able to display these as well. AOL, well, AOL is the bottom end for all 'special features' so don't worry about them further than making sure everything shows up in AOL in a recognizable manner. You can experiment with other fonts that one or the other browsers may not support, like Comic Sans MS or Desdemona, but you should build your font tag so that if the browser doesn't support it, there is one that it does as backup. That looks like this:
<FONT FACE="Comic Sans MS", "Roman">
this should be in Comic Sans MS, but if your browser doesn't support that font, you should see it in Roman
For graphics, choosing a font should be based on both function and design, ie: will the font you choose not only match the overall aesthetic of the page you are building, but also remain legible and understandable no matter what filters or colors you apply to it in the building of your graphic? If the answer is no, don't use it, no matter how cool it looks.
For those characters which don't always translate well into HTML, like '©', '®', and '&'.