With every illegal business you possess, you can earn a lot of money. How many you want to control depends upon your personal situation. Should you be dealt two or more cards from the same business, you should keep these. The more cards that you recieve that are the same, the less your risk is to lose the business to another player. remember that there are four cards for each illegal business in the game. If you have the choice to keep either smaller or larger valued cards, you should decide in favor of the smaller valued ones. Especially as the game advances, it can happen, that you do not have the required value of pieces, and must therefore do without.
Consider well wether you should remove another player off of an illegal business, if another business of the same type is still available.
It is quite enticing to earn a lot of money at once by using your large valued pieces repeatably, but you should not overdo it. Everyone will notice how much you bring in at the end of the year, and your use of the high valued family members. Eventually, the other players will act, and remove your pieces. If you only have the lesser members of your family left, you can not earn as much. You should therefore respect the middle valued members of your family. If late in the game you only have high valued members of your family, you are risking all or nothing by their use.
Revenge is quite a sweet word, however you should not immediately answer every attack with a counterattack. When you do not immediately counter-attack, you indicate that you do not hold a grudge, but often you will pay them back later. If you want to win, your main opponent should be the leading player.
Use your position as the last player in a round to earn a lot of money without risk. You can prepare for big payoffs, by placing your lower and middle valued members early, but still have your Don at the end. In this manner you could easily pocket 100 Riesen ($100,000).
You should not invest all your money in illegal businesses. If you appear to be the leading player, you will quickly become a target for the other players. On the otherhand, if bringing in a lot of money without risk should not be overlooked.
Try to influence the other players with your actions. Divert attention from yourself by pointing out other players' opportunities. You know if it is possible for you to make a totally specific threat or offer. Can't you? Maybe not! Good bluffing is halfway to winning. Remember that all the cards are not in the game, and if you make promises or threats, you may be able to mislead and even stop other people from doing their best actions.