Could you kinldy provide some real insights/tips what is best to do for success with AS as I had tried with single or multiple sites.
Some real insights are found all over this particular forum. There aren't any secrets, although some people will tell you there are. For 19.95 they'll probably also give you the answers. Play clean. Write good, original stuff that people are interested in. Or, conversely, write crappy stuff as a means of inducing ad clicks. Find niches that aren't already saturated and jump in with both feet. SEO day and night. Get good links from quality sites in your niche. Traffic is king and in this respect there is little difference in making money with adsense and maintaining a successful site.
Ads appear but no income
I haven't had that particular problem so can't really comment.
Back on topic. I have no idea where adsense will be in 5 years. The web is still in it's infancy and evolving rapidly. From all outward signs adsense appears to have settled in to stay though.
I know where I'd like to see it in 5 years, or at least what program policy I'd like to see emphasized. I be happy if they'd simply stiffen up their admittance criteria and quit letting anybody and everybody in the program. Thin the ranks a bit. By itself this could only have a beneficial affect on our bottom lines.
Beyond that I don't know. They could start sending me Christmas presents again. That'd be nice.