Run and Gun:
This is for the highly aggressive player who perhaps is looking to complete the scenario quickly.  The idea here is to quickly build up your army with little concern for your cities infrastructure.  First build your Warrior's Guild and then the Ranger's.  While the Ranger's guild is being built, recruit your Warriors as quickly as possible.  The once the Ranger's guild is built, recruit your Rangers.  At this point you begin working on your infrastructure.

Fortress:
The first thing you will want to do in fortress is build 4-5 guard towers around your city and fully upgrade them.  There will not be a monster who can last long in your town.  Once the towers are complete you can work on infrastructure and start building heroes at your leisure.

Miscellaneous:
Wizards have a tendency to hang out in their guild.  To remedy this you can do 2 things.  (1) Place the guild near a sewer entrance so they will be forced to fight their denizens, and/or (2) place the guild on the opposite side of town from the MarketPlace.  Wizard's love healing potions.  They will be forced to walk all the way across town to get them.

Recruiting Rangers early on can be devastating.  They have a way of stirring up trouble.  Carefully weigh the security of your town before recruiting.

Part of the way through the DEMO, 2 Wizards will join your side from a remote land, and then a Paladin.  You will notice that if you have existing guilds that they would normally use (Wizard=Wizard's Guild, Paladin=Warrior's Guild), they will not take up recidence in those guilds.  This is of particuler issue since that means they will not be depositing money in their guild that you can tax.  If you build the guilds after they show-up, they will automatically take up residence there.