From all that I’ve studied and experienced during my internet marketing day job I can say it’s always good to use HTML tags that make sense. If it’s a paragraph use a paragraph tag and if it’s a header use a header tag.

Also if you’re using a header tag make sure you use them in order. Usually I have one H1 tag on the page and that’s at the top and it is the name of the page. Then below that a topic will be an H2 and once and a while I go as deep as an H3.

Why is it important to use tags?

It has been said by Google themselves that they put more weight on keywords found in header, strong and list tags.

When should I use these tags?

Just use them where they make sense. If it’s a lists of items then use the ordered <ol> or unordered list tag <ul> and if it’s a paragraph use the paragraph tag and use CSS Style Sheets to customize those tags.

Summary:

Use HTML tags where they make sense and use a CSS Style Sheet to customize the look and feel.