The Dark Age is the earliest level of developement in the game.  While in this level, the main things you need to worry about are developing your civilization and protecting it.  You should try to do the following:

- Collect Resources (mainly food and wood...you don't need gold or stone yet!)

- Build a small army (10 militia max.) to protect your town

- Build at least 16 villagers and assign 8 to food collecting and 8 to wood collecting

- Explore a lot

TIP: Don't waste any villagers by garrisoning them in the town center!  If you're attacked, just ring the town bell and bring out the militia.

 

The Fuedal Age is much more advanced than the Dark Age, but I still would not suggest any offensive manuevers.  Continue exploring, building, and collecting resources.  In this age you should:

- Build 8 more villagers and use them to begin collecting gold

- Build all the buildings you can

- Expand your army and research upgrades

- Expand your food collecting to include farming and/or fishing

 

The Castle Age is where the real challenge begins.  At this age you are developed enough to mount attacks on your enemy, but their attacks on you will be much more deadly.  In this age I'd advise that you:

- Build 8 more villagers and use them to collect stone

- Build at least one castle as soon as you can and in a strategic location so that it can defend most of your city

- Expand your army to 20-30 troops (varried)

- If you desire to attack a fortified enemy, be sure to build 3-5 rams and bring them with you

- Build a monestary and a monk; use the monk to gather as many relics as possible!

- Research as many technologies as possible, but be sure to get to the Imperial Age ASAP!

 

 

This is the highest level you can advance to.  At this point you basically want to protect your city while at the same time annihilating your enemy.  Make sure you do the following things:

- Continue to collect resources like crazy (if the population limit is over 150, you might consider building more villagers)

- Build many castles, walls, and towers to protect your city

- Increase your army's numbers until you are at your population limit (make sure you vary the type of troops for best effect)

- Build trebuchets and use them to take out enemy castles (it is a waste to send troops at castles, just send them to protect the trebuchets and mop-up the enemy)

- Research as many techs as possible

Tip: When you deploy an army to attack, be sure to leave at least 10 good units behind to protect your city, especially from the deadly trebuchets.