When low on money, make a Temple To Dauros, level 2 (monks), or more recommended, a Temple To Lunord, level 2. Then, make only enough money for the speed up spells (400 gold for Lunord, 800 for Dauros; but it also makes you stronger). Then, find some tax people and cast it on them. Unlike before, they will move very fast and get gold extremely efficiently.
Make a level 2 Dauros Temple and save 800 gold for each Wizard you have. Wizards cost 500 gold. Get the Vigilance spell and cast it on a Wizard. Now he will not only cast spells extremely fast (one to three spells only to get to level 2 from level 1), he will be able to retreat faster then any monster if it gets too close. This will not only save you money in the long run of the level, but will make your kingdom ten times as strong, as Wizards that have reached at least level 6 and heave learned their two spells in the library are easily the most powerful heroes. They can kill giant spiders in as little as one or two shots in higher levels. However, beware as giant spiders can easily kill Wizards early on, as they are fast and numerous.