Monopoly is a strategy game which requires negotiation, resource and management. This strategy will give you the best chance of winning at monopoly and will create a monster cash flow. You will never lose another game at monopoly (well…. maybe one or two).
Think about the positives and negatives of owning a property and try to create groups.
Acquire property. Although you can get high rents on expensive property, Mayfair and Park Lane are not the best options for you best group because of this, if you buy Mayfair or Park Lane houses are very expensive and you are taking a big risk because if your opponent does not land on one of your properties you will soon be bankrupt and it is not worth paying lots of money on high rents which you do not need.
Buy cheap properties to get a steady cash flow and then settle yourself on one of yellows or reds or greens.
Think carefully if you want to directly buy a property off your opponent for money - he will charge extra because he knows you dearly want this property.
The best thing to do when you want to acquire groups is trading - not just giving money for a property. Then, you can be giving a property he can make a group out of and you can make a group also.