The first tip is use a spell checker on your page. Whatever your message, make sure it is spelt correctly. I always have a dictionary next to me and do not hesitate to pull it out to check a word or two. I have used H1 for the main heading size, H2 for the second heading size, and bodytext size 3, in bold, for the sub-headings. Instead, use bold or italics to create an occasional emphasis.
Color is a great way to add occasional emphasis and there are many colors from which to choose.
However, watch your background, light colors on a light background or dark colors on a dark background are almost impossible to read as you can see from this green example. Having sorted out the size of the text, next let's look at how it displays. If you have a page of solid text you will virtually guarantee no-one will bother to read it. You do this by breaking up the page into paragraphs so that the page looks airy and easily readable. An old journalist's trick is to keep the depth of a paragraph smaller than its width, in effect making it 'under square'.