Whoa, Am I doing this all wrong?

I had another thread going but the title was so booooring that no one looked at it lol, so have opened another, (hopef this one is better).

I have just really started doing the xfactor course and after a few test sites and getting my head round it all I now feel that I know enough to really make a go of it. However, after seeing a thread in the fabulous xfactor forum where there was talk of targeting a country for the main keyword and how you could be doing your keyword research all wrong, I am now a bit concerned.

I did ask about this but would like to get your guys opinion.

So just want to know with me being from the uk, should I be doing anything in particular when doing keyword research and when I publish a site should I be doing anything in particular to target a country or leave it as it is.

My other question which is somewhat related is - I have noticed that on some of my websites there are uk ads with .co.uk and such like in the adsense but I really want to target the U.S. Is there a way to make the ads more global rather than uk based?

Some of the answers in the xfactor forum said just forget about all of that and just keep building sites using the xfactor method which doesn't really mention anything about this anyway. (I want to believe this one)

Another answer indicated to find out where most of the keyword searches were coming from and change the target in webmaster tools - site location to point to this country/continent. This makes sense as I checked and some of my keywords, sure enough, are searched for more in some countries than others.

Anyway, I really hope I haven't confused anyone and only want to bring this to attention incase others, like me are wondering about it and don't want to start off on the wrong footing.

I am about to lauch full force into my site building and would hate to think I am doing something fundamentally wrong that could prevent a good outcome.

Thanks for listening and thanks in advance for any help

Yves