I agree your keywords, niche and your traffic volume are the most important aspects to monetizing AdSense!
People think it will be an overnight cash exercise, it takes consistant work every day to make it work - no matter what niche you're in!
The problem is people want money without working enough.......or they jump from one method to another....or they quit them half way.....work without expecting the results...and you will achieve anything and everything......
My answer is: testing, trying... Try new placements, try new niches, try new marketing approaches, etc. Nobody has answer for all question made here, but if you test exhaustively, you'll find each answer by yourself! I have blogs in four or five different niches, at least. When I realize one of them is better than other, I dedicate more time with it. And less with others, that's obvious. Early, I asked so much such questions too, but no one replied me! I learnt I'd need look for answers by myself. Do it too!
Hard work and testing it out, finding the answers as things work or don't work. Sounds good advice! Thank you! Basically there are no shortcuts, aren't there?
Well its simple some people do it right and others dont!! Also some sites are better suited to other methods apart from adsense.