Using Text ads like Adsense/YPN/MSN/adbrite is a most used and very effective way of monetizing a blog. However, not everyone realizes the importance of optimizing their websites to make the most of these ads.
When you are creating a blog/editing the template, make sure you add maximum numbers of ad boxes over the fold of your website. Over the fold means, top of your website that can be seen without scrolling down the page. So, you can use three link ads and two or three text ads at the top.
Further, make sure that navigation area/links are not visible over the fold. The idea behind doing this is to ensure that there is nothing other than text ads to be clicked over the fold. This will mean that visitors either have to close the internet browser, scroll down the page or click on text ads. By limiting the options, you increase the probability of them clicking over the ads.
Regarding colors, usually its a good idea to match the background and text link color that matches with that of the theme/template of your website. Otherwise blue links, maroon links, violet links & white links (with dark background) perform the best as they are prominently visible and visiters usually click over them earning you $$.
If you try my advise, do let me know how it works for you 😉