First I will share my knowledge: 1: I got to http://tools.seobook.com/keyword-tools/seobook/index.php 2: Enter keyword phase and if result for all search engines together is over 5k then I go and check in google how many results it find for this topic. 3: If amount of results is below 300-500k then topic might be excellent . 4: I check backlinks and everything for top 10 results. That's my way ... Let me hear how do you do it =)
I only work on stuff that I have an interest in. Seriously, I have to really like the content I'm dealing with, otherwise I'd get bored and abandon the project too quickly.
Well I have passion for many things but true is that most of this "things" have over 10mil results on google, and it's very hard - almost impossible to get in first page. I also making sites just because of money After I find good niche/topic then re-writer articles or if I find really good topic then I buy them.
I try to do stuff that i have a passion for too. For making money soonest, with more likelihood: I look for market that is already proving itself, say Widget Porn, and then look for terms and niches. For a huge return, but a much riskier, longer term venture: I seek to find the next big thing, for me that's green which seems to be growing logarithmically in the last 12 months. So i determine my goal, my strategy, then go looking for the niches in search to get seen. i think finding a proven industry and trying to find a life there is the best return on invest. I know people who make tons of money in gambling or porn who started just the last couple years. Now those are 2 very marture, tough industries, but people break in all the time.
I look for freshly launched products. I recently found a great one. High demand market, low competition. Affiliate program. Here's more: http://forums.digitalpoint.com/showthread.php?t=846708
One question for experts, i found keywords which have over 10k results in: http://tools.seobook.com/keyword-tools/seobook/index.php When I google there is only 200k results, quite nice heh ? Well only thing that consider me is this: http://www.google.com/trends If i use for my keywords in this google trends site it almost don't find any result's just 1 and it's hell low ... what does this mean???
For any field internet or off line 2 main factor for selecting a niche would be 1. Personal Interest 2. Depth of knowledge and experience In addition to this two, I would consider monetization method available. Consider if I choose to monetize my site with adsense then I would go for high paying terms which less famous. If I choose to promote a product then i would consider the target market and make decisions accordingly. Coming to your last question regarding google trends and seobook kw tool. both are not 100% accurate and some times results will be conflicting , i have experienced the same before many times.
I do a little keyword research at times but i blog content first.I write anything which come to my kind.After 15 posts i ask some of my readers to say me which content they like and depending on that i research more and blog more