Okay, we know we all need to pay bills. I know that many of us want to get traffic to our web sites. And some of us just want to make enough money to pay for our costs so that this thing we love to do is free.
But, come on, that doesn't mean you should plaster a hundred ads or a dozen banners on every page of your web site. A banner here and there, a small button or a few text links is fine, but I've seen some web sites that have dozens and a few that have hundreds of ads on each page! Now this is just tacky and is virtually guaranteed to get your visitors to hit that handy back button fast.
One of worst kinds of web sites, in my opinion, are those that are just huge advertisements. Especially those that are advertisements for dozens or even hundreds of other services. People do not surf web looking for banners, text links and other advertisements to click on. In fact, statistically, most people are surfing because they are looking for (a) information, (b) entertainment, or (c) someone to talk to. Most web surfers are not looking for something to purchase.
A good web site offers excellent content (which can be graphics, text or interactive features). Even those sites which sell something also offer content which is of interest to their visitors. Go take a look at any really good shopping site and you will see what I mean. Look at Amazon.Com or Barnes And Noble and you will understand - these sites offer tons of content. Reviews of their products, consumer comments and large amounts of data about items being sold. This is what people want - information. Some common things on web site that you should never do.
Banner exchanges - It's real simple - these do not work. Oh, you will get a click or two, but banner exchanges tend to look tacky, take up valuable space on your web pages and increase your load time. To make it even worse, many times you will lose far more traffic than you will gain. Don't even bother putting even one of these on your entire web site.
Notices saying "please, pretty please, keep my site free and click on something". This just makes you look like a rank amateur. In my humble opinion, it's very tacky to expect people to click on links just so you can "keep your site free". Come up with or find a good product or service, and sell it if you must. Advertising is not in of itself of value - only products or services have value.