Closing credit card accounts, credit scores

Hi,

I'm new to this forum, so I'm not exactly sure how it works, but here's my question ...

My wife and I recently took out a loan from my credit union in order to consolidate our credit card debt. We've just about finished doing that.

Now, we would like to improve our credit scores (which are not good -- mistakes of youth), in order to one day be in a better position to buy a house. At the moment, we have six active accounts:

Master Card 1 [my card – since 8/06 - zero balance, $750. limit]
Master Card 2 [my card – since 2/06 - $3000. balance, $6000. limit]
Visa 1 [my card – since 8/06 - zero balance, $750. limit]
Discover [my card – 9/95 - zero balance, $3200. limit]

AMEX [wife’s card – since 6/05 - $3000. balance, $7000. limit]
Visa 2 [wife’s card – since 1/02 - zero balance, $250. limit]

I know that it's not wise to close accounts that one has had for a long time, since the length of one's credit history is taken into consideration in determining one's credit score. By the same token, six cards seems too many. So we'd like to keep open as few account as necessary, and use them only in emergencies.

Any advice on how to proceed -- which accounts to close, which to keep open, how to use them, etc., in order to improve our score -- would be greatly appreciated.

Thanks!