Looking for a walkthrough for the skirmish/custom missions..

I have read that these missions are better than the campaign
(usa,gla,china), and also more challenging.
I´ve always been into custom missions and skirmish
because those are often _unlocked_ and you can go on when getting stuck.
This is also why they are harder.
I hate it when I play the campaign, I have to finish all
missions one by one to unlock the next one etc.
Anyway campaign missions are more like practising for the real combat, at
least in Age of Empires and Settlers : heritage of Kings.