Using Common Keywords Is A Common Trap

Search engines as servants
Search engines are programmed to find unique and original content. And even more than that they are programmed to find quality as well as quantity in combination with unique and original web content.
As a servant the search engines work to serve those that search. However, search engines do not directly serve the purposes of small business web sites consulting service. If you want search engines to serve your business needs then your web site must serve the needs of people searching for solutions. In other words, put your market's need to solve their problems ahead of your own business needs.

Doing the ordinary
When you fill your web site with common thoughts, common products and common solutions then your business web site is doing the popular dance with keywords that tries to feed on the traffic volume. But what you are not told is that the big spenders in AdWords are getting the most action. Google favours big spenders and they will always be in the top 3 for the list of AdWords.
What Google is doing to favor the big spender is the same as you giving your best customers a super deal because they spend so much money in your store. You can't fight Google you can only join the club and spend tens of thousands of dollars per month to become one of Google's favorite advertisers. Or you can choose to not play that game.

Search engine servitude
Search engines serve pages. That's what they do whether we search with common keywords or unique keywords. The difference between common keywords and unique keywords is the competition for common keywords. The common search terms are in a dogfight over popular keywords to attract a high volume of traffic.
The unique keywords are not so popular but they are highly targeted. It's not likely someone will type in a long and defined search phrase without having tried the more common keywords first.
Either way, common terms or unique terms, you and I don't fair too well because we get very little traffic no matter which terms we use. If we use common keywords our site is buried somewhere past the top 20. if we use unique keywords we are in the top 10 for seldom searched keywords.

No matter how you look at it there is work to do, just like running any kind of business. The choice then becomes one of working hard to be a tough dog in the fight, or we can choose to build a unique web site that consistently gains ground based on quality and our own strength.

The lowest common denominator
Common keywords are seen as traffic generators, but this is true for very few web sites. In order to be one of the few web sites that get this raw traffic your web site has to be written in such a way that it can be positioned high in search engine ranking. This used to be something like tricks and tweaks where SEO experts charged a high price to deliver the raw traffic. But all that has changed and what your site needs now is quality content - not tweaks.
Meanwhile, no one gave much credit for unique keywords that were easy to rank high for. No one was interested because the flow of traffic was small, even if it was highly targeted. It seemed that sheer volume and lazy search terms trumped unique and highly targeted keywords.

What is unique about your business?
A small unique business making consulting service wooden furniture may have a "Black oak 1860's style wood rocking chair" and if they used common keywords such as "wooden rocking chair" it wouldn't attract their true market.