E = Q x A and web design

Effectiveness = Quality x Acceptance

If you want an effective web presence, you need a site that is of high quality, and is accepted by your target audience.

You can have the most beautifully designed, multicoloured, beautifully written English language website in the world (so Quality = 100%) but your target audience is either
-blind,
-speaks only Swahili, Latvian, and African Click, and / or
-isn't connected to the web anyway
(so, Acceptance = 0%),

... then the effectiveness of your web presence is going to be Q (100) x A (0)= Effectiveness (0).

So, before you build your web site you will need to consider who the target audience is, and what constitutes quality as far as web presence goes. Here are some links that you might find very useful.

World Best Website Awards: http://www.worldbestwebsites.com/criteria.htm
Vincent Flanders, Web Pages that Suck: http://www.webpagesthatsuck.com/
Jakob Nielsen, How users read on the web: http://www.useit.com/alertbox/9710a.html
Navigation and labelling: http://www.d.umn.edu/itss/support/Training/Online/webdesign/navigation.html
Use of colour in web design: http://www.d.umn.edu/itss/support/Training/Online/webdesign/color.html

PS Try and find out what percentage of people in the world are, to a greater or lesser extent, colour blind. The results will surprise you. If you find the answer post it here as a comment!