How to play? Your hero is your best friend (he gets stuff done. Fast!)

Your hero is your most important thing in the entire game. If you are going to spend any mithril, upgrading 1 hero as high as you can is the best thing you can do. Your hero will win you battles, will help defend your city and probably best of all can reduce building times and research times greatly.

For example: lvl 9 fletching takes 6d12h to research, a lvl 212 hero can reduce that to 2d17h. Thats almost 4 days saved. This is true of all research, building and troop training. Your hero goes everywhere, use him, abuse him, and then do it again. When researching, place your hero in the research assignment within the great hall BEFORE you start the research, then after it is started you can move him out. The time bonus stays even if you move your hero.
When you are building things, place your hero in construction just before you start, then move him out when once construction has started. The same with troop training - before hitting go, place your hero in training assignment. This greatly reduces training times and if you can keep resources flowing, your might will increase much faster. The training assignment is also used when defending your city. It boosts any wall defenses and gives your defending troops a defense bonus. This is a must if you ever unhide your troops. Lastly, whenever you are offline or away for a bit, place your hero into production. You'll be pleasantly surprised how many resources you have when you return.