Improving my ability to better determine easier keyphrases with more confidence

Hey guys,
Ive been doing well over the last 6 months or so, and have recently launched a number of sites that are performing reasonably, however, something is still bugging me.

At present Im using Market Samurai, and to be completely honest, am basically going by the colouring of the boxes within the SEO competition module in order determine a go or whoah keyphrase/marketplace. If its green, I go for it, if not, I further investigate. Or I may leave it altogether.

This approach basically tied in with an allintitle within Google to get a better idea of competing sites, along with viewing competing sites themselves within the search results.

Im also careful to check backlinks, domain age and so on but....I dont feel I have full confidence in my ability to determine with absolute certainty that a keyword phrase that Ive chosen is the right one. (let me rephrase that....a keyword phrase that I can penetrate good rankings quickly)

Just recently I launched 2 sites, and both are back at page 16. Its still early days, and I have more work to do to get these up to speed, but I cant help but think that I could have done better keyword/market research.

Im not suggesting that I dont know what Im doing, I just feel that theres something I "dont know" or am potentially missing that is keeping me from acheiving faster, more accurate results.

Is it really possible to launch sites with absolute certainty and confidence? Is this a skill only for the absolute seasoned professionals? Am I overthinking things???

*I should probably mention also that I have a number of sites that have hit first page relatively quickly based on the methods above - whilst others simply drag behind. This makes me wonder how accurate my process really is.