How do I stop Mens & Womens auto-populated collections showing wrong products?

[bigbridge1]

Hi,

I'm building my first clothes store.  'Mens' and 'Womens' will be the top level collections, under which I will have various sub collections, for example garment type (t-shirts, hoodies etc), colour, brand etc. The thing here is that most of these sub collections will be the same for both Mens and Womens.

Because of the number of products, I've chosen to auto-populate these sub collections using tags.  However, the problem now is that under say, Womens > T-shirts I have both mens and womens appearing because those products all share the T-shirts tag.  I'm assuming this is an issue anyone building a similar store has had so I'm hoping there's an easy solution.

Any help would be really appreciated. TIA