Archers are the best troop type in the game. Make LOTS of them.
To make archers you only need your barracks to be level 4. Make lots of level 4 barracks. You should have at least 10 level 4 barracks in EVERY city and it is entirely possible to build farm cities with 16 or more level 4 barracks pumping out thousands of archers at a time.
Later in the game you will be fighting with 50,000 or 100,000 archers!