1.Adsense
2.Infolinks
3.Clicksor (i dont like them)
4.Chikita, adbrite plus many more but cheap.
Things to note:
-Adsense is best cz people are familiar with google and trust their ads.
-Adsense is very strict.Avoid 3rd party advertising sites(those which promise you shortcuts to increase traffic. Adsense will disqualify you.
- Adsense may bring in more but ur blog will determine how much.
-Run it for a while before applying.Traffic is key
-Make use of high paying adsense keywords.Google search engine knows how to pick them up and expose ur blog more.
-You can create more money by having a million blogs.But who has time to update them? One blog is enough work!
-Adsense ads appear as blocks,infolinks appear in btwn text with double underlines. Not attractive.
Your blog must have lots of texts for infolinks to work.
The most important thing with blogs is traffic.
It's the heartbeat of any blog cz it's traffic that brings in money constant updates,will really help.Links,mail follow up,proper gadgets too aid.
I prefer adsense or infolink or both in a blog but it will look clustered and ugly.
Besides ur adsense revenue will reduce if u do both. I got that from a blogger.
Ok go for it but don't expect much at first.People earn cents after months cz they dont know how to make their blogs attract traffic.
I create blogs as a hobby but I've decided make the hobby a lucrative one.
Right now am building traffic b4 i apply for ad or info.
"The true measure of a man is how he treats someone who can do him absolutely no good.