This walk through is based on a human city but is general enough to work for both orcs and elves
So you've started your city and completed the first few quests and now you're watching your peasants gathering wood/food. You've built your first unit of workers and a house or two, now what? Well quests will come along to help get your feet wet and using your troops about your home city map. If it's summer, build a mill right off to provide a steady supply of food that's easy to guard. The wolves that roam the map like to munch on villagers and will do so at every opportunity. Always remember to loot the creeps you kill, that gold is a useful resource. A market is also something to build early on to provide a place to trade gold for resources without leaving your town. Otherwise trading resources means a long trek to an NPC town that carries what you wish to buy.
Should you be joining the world of Mythador in winter, build either a barracks or archery range. You will always want troop producing buildings in your city and the earlier the better. Even if you don't have the resources to buy troops from the building right away, your peasants will work while you're offline and you can log in to find your larders refilled. Horse carts will be your mobile larders when in your army and on your home city maps or battle maps of any kind your peasants will drop off the resources they gather.
Bear in mind that the more houses you build the more population and resource capacity you'll have so build them often! The more military buildings you have the more troops you can create whilst defending your fair city from those vile attackers. A siege workshop will allow you to upgrade your siege weapons and wall defense. A Blacksmith will allow you to build stone walls and is often an early built building.
After you finish the first several quests it's time to travel about the world map to visit quest locations. However a large bonus of creating an army and questing is the ability to "view map" that armies have. This useful local will allow you to loot all those pesky creeps and level up your troops to make those quests easier. You can also siege NPC towns for a big resource boost (limited to the amount of resources your army can carry). For more info see Help I need gold!
By now you should be well on your way to a ten villager unit count and harvesting wood for new buildings all over the map. If you have extra resources, find an NPC town with cheap wood to help the building boom. At this time begin to stockpile military units in your town and prepare to build your palisade walls. If you prefer you can research Masonry at the blacksmith to get an option to buy on stone walls. However this will slow down your wall building abilities immensely. By now you've reached the end of your day (most likely) and the end of this guide and you've learned how to gather resources and stockpile, start crucial buildings,complete both homeland quests and travel quests, how to purchase mercenaries and resources from NPC merchants. You're now well on your way to being ready to hand out pvp smack downs on day two (or late on day one).