The advice Rhythm offered is an ingot of pure gold.
Some of text design and page layout has to do with your audience. What’s good for older readers won’t necessarily attract young whippersnappers, but nobody want a headache.
For the websites I’ve created, I list fonts like DreamWeaver—the professional web construction program—does:
verdana, arial, helvetical, sans-serif.
This should cover 99.9 of the computers out there. Use no faces that are overly bold, and nothing too thin; and, (as if your life depended on it), avoid using anything that might be described “swoopy.”
I used three sizes of type:
heads, 30 or 36 pt, maybe in dark red or soft blue.
subheads or kickers 18pt. Maybe in black bold.
text, 12 pts.
Whatever you do, be consistent! Make templates for speedy construction.
People don’t like to read online—except here of course, but then we’re a peculiar bunch. Make the page easy to scan and then keep the copy as short as possible and still get your point(s) across. Go easy on bold or italics. Use bullets. Separate paragraphs with a blank line.
When I was first learning web design, I was told that I had 3 seconds to hook my visitors, and that any page on the website should be accessible in 3 clicks. This 3 clicks rule has been softened over the years, but it’s still has merit.
Find a website you like and check VIEW > SOURCE and see what they’ve done.
G’luck.