Starting Narrow and broadening up

Hi guys,
On day 2 I chose my site concept as Mind Maps as the numbers are good and it is not too competitive. My initial plan is to start with Mind Maps and then broaden up adding other tier 2 subjects such as Speed Reading, Brainteasers and Memory...

Is this the right way to go? Will my site be to unfocused for a keyword? The only keyword my tier1 page can go under is really self improvement or the mind.

I plan to tackle this like Nori did ( anguilla-beaches.com )
She grouped all of her tier2 pages together (go to her site to see what I mean.

For my site... my groups would be Mind Maps, Speed Reading, Brainteasers and Memory then my tier2 pages would be specific areas of the tier2 pages eg
Mind Maps
Overview (link)
Using them (link)
Why Mind Map (link)

Also, if I choose to broaden up, what my site Concept actually be... The Brain?
Would I then have to brainstorm the brain/ mind?

Would this work? I am really stuck about this...

Cheers,
Charlie