Because cracked servers attract a younger, less patient crowd, griefing is rampant. Never share your base coordinates. Never trust a player who says "I'm friendly."
To join these servers, you cannot simply use the modern Minecraft launcher. You will need a launcher that supports "old" skin fixes and historical versions. The Betacraft launcher is the industry standard for this, as it automatically fixes the broken skin servers and sounds that usually plague older versions of the game. Once your launcher is set up, you simply enter the IP address of your chosen cracked server in the multiplayer menu. The Legacy of the Golden Age Minecraft Beta 1.7.3 Cracked Servers