When choosing keywords for your website, it's important to understand that not all competition for keywords is created equal. I'll give you an example to show you what I mean.
Imagine you check the keyword for "large dog collars" into Google with quotes. And the results are 25,000 competing sites. Next you check the keyword "how to lose weight fast with xyz". You check that keyword and the results say 25,000. You may believe that it's just as easy to create a webpage optimized for the weight loss keyword as it is the dog collar keyword. However, that's not the case. Here's why:
The sites that are competing for the dog collar keyword are created by people probably not as SEO savvy as the weight loss group. In their words, in the highly competitive areas such as weight loss, even if you find a relatively low traffic keyword, it is not as easy to rank well for that keyword as it is in an area like dog collars where there may not be as many SEO professionals. In the large areas, there are more SEO professionals optimizing for those pages. So even if the competition is the same for a keyword, the quality of that competition may be very different.
It is far easier to use SEO and rank well in smaller areas than in large areas regardless of what the individual keyword competition shows. It's very important to remember this because many beginners choose to go into those large areas such as weight loss, dating, home foreclosures, etc. thinking they can find keywords which have little competition and then be able to write for them. Always remember that in those large areas there's much money to be made and where the money is, the professionals will follow. Not nearly as many professional SEOers will be creating sites in the smaller niches that aren't as lucrative.
So do your homework and research the areas well. If you spend your time in the smaller niches, you will have less competition and faster results.