One of the most glaring amateur mistakes is use of multiple font choices, sizes and liberal use of styling elements like italics and underlines. For a professional page, you want to keep it simple. Use a single font for the body, and italicize, bold and underline sparingly. If you must use a different font somewhere on the page, make it in header titles. Separating sections with larger bolded text, even in different font, is perfectly acceptable.
The watchword is really restraint. Keep it simple, value the balance of null space, and put your artistic inclinations into pictures and interface design, not in the body of the content. Don't treat your website like a flyer for a local high school perfomance of "Cats". Treat it like what it is, an informational tool for your business and the first contact for potential customers.