The SOLID principles are the foundation of building good software. They are the breakers of monoliths. The decouplers of coupling. The squashers of regression bugs. One might even say that they are the creators of maintainable code.
Unless you already a believer, you need to attend this session and get on the right path. Chris, the bringer of SOLID knowledge, will go through each one of the principles, explaining what it means, what it will do for you, and why you should stop breaking it. You will even be shown C# code that explains how they help you, and what problems will haunt you if you ignore them and are faced with their wrath.