On monopoly city streets, one of the most important thing is to protect your street. You can do this by the chance cards received by you from time to time. You can build a school or a stadium and your street will be protected.

However, another chance card, will demolish your building, so it's very important for you to build more than one building. I usually keep around 9 buildings/street because there's a very small possibility for someone to get 9 chance cards to demolish all of them.

Now as a strategy, I bought a separate street of 4 million and I use it only for chance cards. On this street, the only thing I'm doing is buying small houses , then sell them and buy them again till I remain out of money and houses. I usually keep at the end of all my updates, around 1-2 millions and use them for house buildings when my enemies will start building hazards.

One of the most important thing is to always check your account with 2-3 hours before the update, to see if anyone buldozed, or placed a hazard on your streets. If not, then spend the money kept before.

As a piece of advice, don't attack anyone who doesn't attack you. It's better if you keep all your money than gather enemies. Try to defend yourself and don't attack them unless it's absolutely necessary. Most of the players have formed alliances and they can attack you all at once.

These being said, have fun and don't forget, this game is for play and fun, so enjoy it.