1. High politics: This hero will increase your production of resources from your resource field and also speed up time of building. You need to develop the habit of changing from one hero to the other as required.
2. High attack: This hero is used for training of troops and when you set troops in the barracks apply this hero before hand. Also used in attacks to give an advantage over a lower attack level hero so be careful that you use this one when attacking.
3. High intelligence: This hero is used to speed up the time taken for research so apply this one before starting research in the academy. A word of warning here is that if you start research with another hero do not stop it to change heroes or you will lose all of your gold. This time difference may seem small at first but as you get to higher levels with research the time increases greatly. Archery to lvl 9 is around 250 hrs from memory and the wrong hero can add more than 50 hours to this time.
   Another use for the high intelligence hero is finding medals in valleys and flats. when first starting a low level hero is fine for attacks on these valleys and flats so use a higher intelligence hero to give yourself a better chance of finding medals. Using heroes in these attacks will increase the attribute so you will decrease the time taken for research further and other tasks.

In the early stages use all your heroes for valley and flat attacks to increase their attribute and gain the advantage that each then gives. We all tend to concentrate on just the one hero for these attacks and that is usually the attack hero but do yourself a favour and use all three.