I agree with you. you have to work very hard. There's no hidden tricks. For more details read this article. http://hectornicolas.blogspot.com/2008/08/are-you-newbie-blogger-memorize-this-5.html
1 - Unique content 2 - Drive targeted, organic traffic 3 - Blend adsense ads to match your site's layout
haha.. i beat you to it then. I've never been a big fan of traffic coming from social bookmarking sites as those folks tend to increase your page views but hardly ever click on ads and ultimately drive down your CTR.
while its easier to do SEO on niche with no competition, it will be usually low paying niche at the the end. all the high paying or even decent paying niche will have competition