Let me first say welcome and the best of luck in all of your endeavors. Let me give you a few quick tips
1. Make your blog niche, at least your first or main one, something of interest to you personally.
2. Regularly update the site with posts, links to relevant content, and rss feeds relating to the niche. This will give people a reason to return and help create a sustainable traffic level.
3. Visit other blogs related to yours and post comments with links back to your site. Contact the author and let them know you are linking to their site and ask for them to return the favor. Do this early and often as this will help drive traffic to your site and up your standing in the search engines. Post meaningful comments don't SPAM.
4. Add affiliate programs.
Clickbank - Make Money Selling Digital Products
Traffic Payouts - Promote the #1 Converting Work-At-Home Product!!!!
Have a website? Earn money with LinkShare merchants.
PayLoadz : Sell Downloads Online
ROI Rocket - Make Money!
5. Diversify not only your sites but your advertising. Obviously use adsense but also try BidVertiser. it has a really good program. Another one to try would be AdBrite
6. Market your site via myspace. you will need to join some groups and forums and then post topics and bulletins. find people in these groups and forums and add them as friends. Add as many friends as possible. Once you begin to build a network you can start posting bulletinsand sending messages to market your site. Also post comments on friends' sites with links back to yours.
7. Visit forums related to adsense type programs, blogging, making money, entrepreneurship, small business, etc., and any related to the topic of your niche and post to them. Don't just post crap as this will work against you. Post honest thoughtful comments and information. Register for these forums and put links to your sites in your signature and when appropriate your posts. Don't SPAM
8. Remain dedicated. It will take a lot of work in the beginning. Set aside a set amount of time each day to devote to your effort.
later all and have a profitable and productive day.