Building houses and hotels
Building advances your ability to bankrupt your opponents. Many players build all they can afford. However, this strategy results in losses when houses must be torn down to pay rents or other penalties often.
You should build when you form the first complete color group.
You should build when you can do so and still be left with enough cash to pay a "high probability" expense - namely, rents on Railroads or Utilities, Luxury Tax, and the "nasty" unexposed Community Chest or Chance cards. $150 to $200 is all the cash you need to hold onto if there are no other complete color groups against you. $300 to $400 in cash is recommended if there are one or more complete color groups developed against you.
You should build late in the game, in "all or nothing" situations if you think you can financially cripple an opponent by doing so.
When you build, build according to these principles: Build a color group up to at least three houses per property before you start building on a second color group. (Note that rents rise dramatically once a third house is added to a property).
If you can afford an extra house, put it on the most expensive property of the color group.
Build up to the fourth house or hotel level only if you have plenty of cash to spare, unless the group is one of the first three on the board (Dark Purple, Light Blue, Light Purple). Due to the low rents of these groups, you should try to build hotels here.
Early in the game, develop a low rent color group as soon as you can in an attempt to bankrupt opponents before "heavier" color groups are developed against you.
When buying a second extra house for a three-property group, put it on the middle property if the group is Light Blue or Orange. Put the house on the first property if the group is Light Purple, Red, Yellow, or Green.
To make beneficial trades, you need to be familiar with some basic principles.
Early in the game, for instance, trade to get low cost, steady income producing properties: namely, the Railroads or Utilities! (Railroads are preferable over Utilities).
Try to trade for a complete color group that can "dominate" quickly.
To complete a color group, your best trading material might include the Railroads, the Utilities, or the Dark Purple group, as well as single properties that do not yield an opponent a more dominant color group.
When trading developable properties, try to trade for properties of equal or greater value and those that lie closer to Free Parking.
Determine which color groups to trade for, based on what you can afford to develop, and which groups have a better chance if redeeming your investment.
If you end up with a completed color group whose dominance comes later in the game, don't overextend yourself. The lower-rent color groups are likely to give you trouble if you deplete your cash too early. Be patient until your assets grow.
Trade for cash only if your "gain" is likely to be more than your opponent's. This means that he or she shouldn't be able to afford to develop a completed color group as a result of the trade. You, on the other hand, should be in a position to put the cash to good advantage - by building further or bolstering your cash reserves.
Use common sense. Make a trade only if you're sure it will improve your chances of winning. Don't allow another player to persuade you to trade just for the sake of trading.
When you interest an opponent in a trade, try to let your adversary do most of the suggesting. You may get more than you thought you could. (Nevertheless, if you feel you can show your opponent why a particular trade is worthwhile for both of you, don't hesitate to demonstrate why). Try to show your opponent why his or her demands are too high if you are unwilling to pay his price.
Get the maximum out of Mortgaging
Mortgaging is essential to raise money at crucial moments in the game. Follow these guidelines when it comes time to mortgage.
Mortgage single properties first. Try not to mortgage a property from a group where you own 2 or more properties unless you absolutely have to. (You can't build on a color group you own if one of its properties is mortgaged).
Mortgage single properties to raise cash if it helps you develop a color group up to at least three houses per property, (or hotels on the Light Blues or either Purple group).
When you must decide between mortgaging properties, use this list to prioritize. Try to mortgage first colored properties closest to GO, then a Single Utility, then Railroads and last The Utilities (Utilities produce a lot of cash, and you will need cash to unmortgage properties).
Bear in mind, though, that Illinois, New York, and Boardwalk have higher chances of getting landed on than many of the other properties, with Illinois the highest. Don't mortgage these properties if you can avoid it.
If your opponents develop more expensive color groups, resist the temptation to mortgage heavily to develop a lower-rent color group to your limit, unless you're in an "all-or-nothing" situation late in the game.
Pay off mortgages only if you have developed your completed color groups to at least three houses per property and can afford to unmortgage.
When paying off mortgages, pay them off in the reverse order in which you mortgaged them, unless you can develop a new unmortgaged color group by doing otherwise.