Devlounge has a short article with the basics on how to monetize a blog without creating a horrifying mess and driving people away.
We’ve all seen it: websites and blogs that offer up great content suddenly becoming littered with ads. Sometimes it happens overnight- but more often than not, it starts slowly: an ad here, some Adsense there, another ad here, and so on- until the blog looks like it’s almost all ads, but you really can’t tell, since the ads look so much like the content. Sound familiar? When this happens, there’s just one thing I want to do: leave the site.
Now I’m not saying there’s anything wrong with monetizing your blog- not at all. Just that you can do it without necessarily uglifying your previously clean and beautiful site.
The tips that follow are pretty good, some of them are virtually common sense. Have a look at the article, especially if you’re new to the world of advertisements.
My advice is to use 125×125 ads, or something similar. Use Buy Sell Ads, or sell them yourself.