OLD INFORMATION:  I will be updating this very soon.
BUILDINGS
I suggest you spend some time in the "Building your Providence:"  area of the GUIDE TO UTOPIA.   Buildings are a major part of the game.
In general it varies some for each race.                   The follwoing tips are vital to all:
Use the INTERNAL ADVISOR to plan,  I use the percentages listed there to calculate my build.  DOWN LOAD ANGEL from UTOPIA TEMPLE (The address is on my main page).  ANGEL provides a building planner.

Inital building percentages for key buildings:
IF YOUR NEW:     Rules of thumb:
Armories are important for all races.  They reduce training cost and now train elites.

Guilds are needed by all:  for defense only i suggest 14% ,  If playing MAGE to the max i suggest 25% (18% is threshold for a great mage).

Towers - Vary by race :   Mages run 15 - 30 percent, most opt for 8% in towers and use thieves for extra runes.  (Stealing runes requires few thieves and is a very effiecent operation to use)

Houses-  I opt to destroy them.  Although i know of people that use them.  ORCS and AVIANS are know to have a few in certain radical builds i have seen.   I opt for science instead though to add bonus housing.

Watchtowers -  If you are gonna be a top thief get a good many (Max is over kill though)  Science helps alot ..  For basic help in defense,, rule of thumb if you are being owned way more than you want by thieves,  get 10%.

Libraries are a nice help, i have played using 100  built by end of protection and found i could max science by 100k networth.  (Note max affordable science)

Schools -  I kinda like them after 100k  they help get your economy rolling.  I opt for them at times.   If your playing solid growth i suggest you consider them in the 15% range of your build percentages.

Dungeons - I have not used these, but I know that serious Attackers often use them.

Stables -  They are a good way to add offense,  I usually build/thief/mage due to the time constraints on my play, however if you play attacker consider them ,, Rule of thumb each Building adds space for 100 horses so if you plan to use 4000 you will need 40 stables.  10 stables per 1K troops that will be attacking.

Hospitals -  I can't say enough about this one.  Especially for the Feary players.  They are a must in fast early builds.  and offer great recovery ability during long wars.

Mills -  If you are sharp and use prophet (a free game planner from Utopia temple , downloadable) right you will figure out their value (HINT) try running a build using them in your first built land.  hehe few tips here !!
THIS IS HOW THE GOOD ONES DO IT>
Estimate land at 600 area, put in enough buildings to reach the MAX on their bonus (SEE GUIDE)
After you get all that land going ,, rebuild them into armories around hour 38 ,,,  play with it you will get the idea.

Farms - Some races don't need them and one uses double (UNDEAD and DWARF respectively)
Rule here is 8% of farms if you cast fertile land along.
you need about 18% for dwarf..   HOWEVER  SCIENCE IS UNREAL CHEAP .. played right you can cut regular play number to 5% with fertile land and get Dwarf near the 10% mark.

MINES / BANKS
I use both theres a macro in Angel (the download i spoke of )  that helps give you the ratio you need..
If you have it cast Mystic to help the miners.