How to use keyword decoration effectively.

Hi.

I need a bit of clarification on how to use keyword decoration effectively. I didn't know anything about this before, but then read about it on a blog and started to implement it. However, I'm uncertain about a few points.

At the moment I use it just once on my keyword. I've since seen other websites where they seem to use it loads of times on the same or similar keyword. Is this seen by Google in the same way as keyword stuffing? Therefore, how many times should I use it on the keyword to be most effective.

If I've got another keyword that I'd like to target but it is not my main keyword, can I use decoration to make it visible to Google and does this make any difference, or is it only the main keyword that is used to 'rank' the page.

Appreciate any advice,

Thanks.