I'd suggest trying to make your keywords as specific as possible. Let's use dogs as an example. People doing searches tend to be looking for a specific type of dog. You'd have a better chance of ranking for a specific breed of dog (i.e. a Tibetan Mastiff), than you would for dogs in general. "Dog" is such a broad term that there is likely a lot competition for it. Tibetan Mastiff, being a subcategory of dog, is a specific term. So by using a more specific type of dog, you are weeding out all of that extra search result noise. Without all of that extra noise, your odds of receiving traffic improve considerably. Hope this helps!
start with specifics. And normally the specifics keywords (long tail keywords) includes the big keywords. This is a very stupid example: "Dog training Chicago" includes "Dog Training" "Dog training Free" also includes "Dog Training" if you start to rank well in those 2 long tail keywords, you could rank for the big keyword also.
i am 100% agree with you i have done this and had got much benefit from this. thanks for share knowledge about it. Thanks