Here's a hot one on keywords which led me down an interesting path.
I'm still missing a tool which can get the near-misses in terms of synonyms and spellings, etc.
I'd always been spelling self-help with a hyphen. So when you search this against personal development and self improvement, it comes up second or third, depending which country you're looking from.
However, more people spell it "self help" - with a space. And this is way more popular than personal development.
Now I've got all these pages optimized for "personal development". Text links and all that. OK, so? Means I can double up as I can through these pages and then also command niches in both long tail search terms - or all four. (However, "self-help" and "self help" are both more or less the "same" search term, one ranks higher...)
Turning this sow's ear into a silk purse, I can see that I could now take similar pages and optimize the same material into all these niches. Great stuff.
Now you can search for Go Thunk Yourself Self Help Library as well as Go Thunk Yourself Personal Development Library - your choice.