Internal SEO keywords - have I got it right? Is this going to work?

You're overthinking this, so I'll use an example to make it a little easier.

Let's say your business is selling collectible coins. Obviously, your main keyword for the site is "collectible coins" and you'll want every blog to revolve around that theme. So you'd go do some keyword research to see what people type into the searches when looking for coins, and that's how you get your top five keywords.

Now, let's say you have some collectible stamps you want to talk about in a blog. Your very first sentence in that blog could be- "Although we normally discuss rare and exotic collectible coins at <site name>, I couldn't help but mention these amazing stamps that I purchased at auction today." Then Google still sees that you're focused on coins but talking about something else....and that's perfectly fine.

Just don't take that advice too literally, because SEO is not about keyword stuffing at all anymore. Use your keywords when they fit naturally, and don't worry about it when they don't. Your only real goal as a blogger is to get people to enjoy what they're reading and click ahead for even more. As long as that's happening, then the keywords aren't nearly as important overall (as long as you are using them sparingly).

Right, got that. Thanks for the help. I was admittedly freaking too much over keywords.