When I was a kid, I read a book like the one Frayed Knot describes in a desperate attempt to finally beat my big sister. Of course by the time I learned all the secrets of victory she was no longer interested in playing games with me. Railroads, Oranges, Light Blues, and Reds are best both on cost/benefit of investment and the likelihood other players landing on them. The dark greens actually require a huge investment with disproportionately low returns. There's also little benefit in building hotels, just stop at three houses except on the Light Blues. No one believes it but if you get hotels on Oriental, Vermont and Connecticut it is a killer. It doesn't have the one-time wallop of PP and Boardwalk but your opponents will land on one of them every time around the board and be slowly sucked dry.