Entire books have been written about writing for the web. They have titles like, well, Writing for the Web. Also: Writing for the Web: A Practical Guide, Writing for Multimedia and the Web, and the nicely alliterative Killer Web Content. I imagine these books are used in Marketing courses, and I'm sure they contain many sensible words of wisdom. But honestly, it's hard to imagine anyone needing to study a whole book to learn a few basic principles.
For pretty much any home page, these principles can be summed up easily, as follows:
• Use concise, accessible language.
• Give the key information right up front. (Explain who, what, where, when, and/or how, as needed.)
• Get it right. (Don't allow any spelling or grammatical errors to get through your proofing process.)
• Make it easy on the eyes. (This is partially, but only partially, the web designer's responsibility.)
Here are a few examples of sites that get these things right and wrong.
Let's say I live in New York and I want to find an electrician. When I search for "electrician new york," among the top entries is Altman Electric. Altman's home page provides the essential information right up front: where they're located, what types of customers they service, and how to contact them. It meets the four requirements described above: no technical terms or excess verbiage, key information up front, no grammatical or spelling errors, easy to read.
Now take a look at another top search result, Apollo One. This home page fails on most counts. It doesn't look good. The text is too low on the page and full of errors. There's no mention of their coverage area except for the phrase "in New York" at the top, which is ambiguous, as "New York" could mean Manhattan, all of New York City, any of a number of conceptions of "Greater New York," or even New York State. For all I know, Apollo One could be a better deal for me than Altman, but I won't be finding that out, because if I need an electrician fast, you can bet I'd call Altman first.
2. Database Developer
Let's say I need to hire someone to develop my company's FileMaker databases. I search the web for FileMaker developers and I find Scottworld. Their home page has most of the bases covered. The font size is smaller than it should be, but the essential information is right there in the first two brief paragraphs, explained in plain language.
There's one thing missing, though. How do you contact them? You have to scroll almost to the bottom before you spot a tiny "Contact Us" text link. It took me many seconds to find it, by which time my eyes were tired.
Now look at Excelisys's home page. This one has more serious problems. It's busy, colorful, loaded with logos. The key text is contained in a white-on-black box, which makes it a little hard to read, and it begins with a sentence that isn't even a sentence and is dotted with extraneous capital letters. The rest of the text suffers from grammatical errors and incorrect punctuation. While the site has a lot of material I could review to get an idea of what these folks do and how well they do it, I'm not likely to click through to see that material, because the home page has made a poor impression.
Search for anything you like, and you'll find examples of bad, better, and best-practices home pages. Make sure your own home page follows the simple principles outlined above.