The pilot reported that he was taxiing to the active runway for takeoff, when the windshield started to fog and he missed the left turn to the runway. The airplane exited the taxiway onto a grassy area, and the pilot then turned left; however, the airplane began to slide down a hill. The airplane's right main landing gear collapsed and the right wing impacted the ground, which resulted in damage to the right wing spar. The pilot did not report any mechanical malfunctions with the airplane. He reported 1,400 hours of total flight experience, which included 96 hours in the same make and model as the accident airplane.