So, if you take trouble to make your HTML tags specifically used for what they were intended for, how can you make your web page look "cool"?
Use a style sheet. A style sheet is a file which tells a browser how to render a page. There are even aural style sheets [coming up -1997] for telling a speech browser how to pronounce different tags.
A current recommendation for style sheets is the "Cascading Style Sheets" (CSS) language. Other languages may become accepted in the future. It allows you to specify many more things than you could do in HTML when it comes to color, font, position and generally where and how something is presented.
Why is it useful to keep the style defined in a separate document? here are some reasons:
Have fun with style sheets. Also, within a company or a series of publications, use them to establish conventions which tie a given look to documents of a given status.