Instructions
Know the game well. Understand the equipment to the game. Know that there are a limited number of properties and houses that you can purchase. Know which properties require which rent payments and how to use the Chance and Community Chest cards. Know the rules of the game so you can develop a solid strategy that works.
Know how much money everyone has. You can pretty much estimate that each of your opponents will earn about $170 in a trip around the board. Also know that each person starts out with $1,500. If you can keep track of how much money each of your opponents has, you can have a leg up on winning the game by knowing what they can afford to buy.
Buy unowned property if no one else owns any of the properties around it. This can allow you to capitalize on a new property venture. Also, buy unowned property if it can block another player from owning all the properties in that area.
Determine when the best time is to build houses and hotels on properties. Build on properties in order to move toward bankrupting your opponents. But don't build on properties if you can't afford to do so. Too often people build on properties as long as they have the money to do so. This can backfire when you have to make rental payments on your next trip around the board and have to sell those newly-built properties.
Learn how to mortgage wisely. If you have to mortgage your properties, learn to get the most out of it. Only mortgage properties that give you the amounts of cash you need. Mortgage properties that have the least likelihood of being landed on in the next turn, as well.