Is it better to have similar or different keywords on different pages of a website?

[Ali]

I am working on updating the keywords on my company's website, and I am getting different, conflicting advice from different people.

One person suggests that I should have similar keywords on most of my pages, in order to strengthen my position with the keyword.

Another person told me that I should have as many different keywords on as many different pages as possible, in order to get a wider audience.

This is a small business website, and I am trying to boost traffic. How should I proceed, and which advice should I listen to? (Or should I ignore both of them and do something completely different?)

Any advice would be welcome. Just don't suggest going to a SEO firm.
I have already been making informative blog posts to supplement the store, but I have had almost zero traffic on them. These ranged from How-To posts about some of our products to helpful tips within the field.

I already used the Google webmaster tool to mark them as articles.