Complete sets
Three unrelated cities earn modest rent. A group of three cities in one country doubles base rent and unlocks construction. Follow your opponents' deeds as well as your own: an auction or a timely trade for the last missing city can change the match. Avoid overpaying because a tile looks attractive.
Keep cash available
Before developing, calculate your total building costs and what remains for a possible opponent's rent. Selling upgrades only recovers part of their cost; mortgaging cuts off rental income. A reserve often beats building too quickly. Holding more than one airport increases airport rent; utilities depend on the visiting dice roll.
Choose the right moment
Every bid changes another player's opportunity. If someone is one city short of a full country, value the deed based on the benefit to them. In debt, sell building levels evenly or mortgage a less useful deed before giving up. Surviving another round matters more than winning every auction.