When i create first site my adsense income was not more then ten cents, yap not cool 
but this was only first income. i will tell 6 tips for adsense to get first income from your site, no matter what kind of web site you have, this tips would help to get first income in adsense.
1# First of all you must add at your page some interesting content may be this will be articles, news or something else, if you have written over 20 articles this is good, but you must write articles yourself, this will be perfect for the popularity of site. Then you will adding some more articles.
2# Now you must choose ads format. more popular is 336×280, 468×60, 728×90, you can add only 3 ads per page and add it.
3# Color of your Ads is one of the most important, when anyone will be visiting your page he must see ads well. you must choose your page background color for ads background color, your link color for ads title color, border must be like page background but this is optional, you can choose red or blue color for it, for text and url color you must choose colors that you are using at most in your site.
4# Ok you add Adsense For Content? good, now you must add Link Unit. You can add only 3 link units at one page, I always add only one link unit at one page, but this is optional if you have good position for Link Unit then you can add 3, and you must choose colors like you have chosen for adsense for content.
5# If you already had added your site into search engines, then you can add Adsense For Search at your site, if Google can’t found your content you can use Web masters Tool to add your site map.
6# And last to get income you must have visitors, you can use Google AdWords, Adbit, Yahoo Search Marketing if only you have money, but if you have not ? if you have not have money for your web site to bay advertisement you can get visitors from forums, blogs, and from digg.com, stumbleupon.com if your site or blog will be interesting, visitors will come back, with this method you could not get high number of visitors, but this is only for start, when you saw that your site have some income then you can use some advertisement program like AdWords or YSM(Yahoo Search Marketing) to increase your revenue.:)
I don’t like #6. If the only income you make will be from adsense. Then arbitrage with programs like adwords will lead to a negative ROI.