Replying to Leg cramps and soreness

Hi, whenever I go skiing after like the second run I start to get really bad soreness and sometimes cramps in my quads, and I often shake uncontrollably in the legs. I don't ski very often mabey 8-10 times a year. Does this mean I just dont ski often enough or am I doing something wrong. I should ad that im an intermediate skier who skis mostly blue squares and black diamonds. Does anyone know of some excercises I could try that could help with my issue?
Thanks
-Cade