Advice required on long tail keywords

Hi

I'm hoping that someone can give some advice. I've read on various blogs and websites that it's possible to earn income through only targetting keywords that get low monthly searches in the region of 100 - 1000 or even lower instead of targetting phrases that get around 1000 - 10000 searches per month. I realise that the amount of traffic that will come to the site will be less obviously. However, I'm thinking that perhaps it's easier to get a first page ranking with very low searches due to less competition and perhaps some of these won't require that many backlinks to get them to rank. Can someone identify with this approach of earning an income with adsense or affiliate products?

The other question is, should writing articles around these low search phrases be placed on web 2.0 sites such as Hubpages and Infobarrel or created as subdirectories on a generic domain which I already own? I would to do this than purchase a domain for each keyword.

In other words, is it possible to build up to earning say $50 a day through targetting very low or low search keywords. Instead of building links to higher search terms, I would be writing content around lower search terms on my own generic domain and possibly Hubpages and Infobarrel that can help to build links as well as earn some extra income? I realise that it would involve writing a lot of articles but I'd prefer to put these on my own website or revenue share sites.

To get the articles to rank on the first page of Google, what amount of competition in intitle should I aim for? I realise that it's important to also look at the page rank of the sites ranking on the first page.

I hope someone will reply.

Thanks