If you have enough money and employees, you can choose the most popular keywords for your site. Otherwise, choose the keywords that are less competitive.
you should found the keyword related to your website like if you made the web on worldsports you will type international sports in your google search engine or anywhere you are going to logged . ok
I use Micro Niche Finder and Google adwords together and try to apre down the list from there. I still need alot more practice with both. Just stick with it and you will do find.
Only you can answer that question. Why do you want to put a website up in the first place? What is your objective? What do you want to accomplish? Some people put a site up to share information. Maybe they know alot about a subject and want to share it with others. Other people put a site up for the sole purpose of making money. If that is the case, you need to decide how you want to do it. When people talk about Adwords, high CPC etc, they are talking about Adsense. A few years back, that was very possible by putting up a lot of Adsense sites that would make say $5 per day. 20 of those sites would give you $100 a day. Those days are gone. Those type of Adsense sites are being pulled down by the hundreds) Of course I am talking about Google. If you are new to IM, an Adsense site is the last thing I would start out with. If you love to write about something and can offer something to your visitors, by all means put a site up. Get a good following going and then slowly consider putting advertisesments up. If you are only interested in making money with a website, you need to first learn the many different ways of doing it. Affiliate marketing is probably the easiest and can be very rewarding if done properly. But again, it depends on what YOU want to do and what YOU want to accomplish. Hope this helps a little.
If you have something to write, just write. Those tools are not for real writers. I don't think that real journalists, doctors, etc. worry about keywords before creating a new blog post.