Replying to Soreness

So its the wintertime and i only have 2 steady routines, downhill skiing and cross country skiing. These two sports dont really get me sore because im used to the workout. Occasionally however, i go to the gym or go to our indoor skatepark and ride bmx, and these two workouts just put me out the next day because of soreness. I was just wondering, other than doing them frequently, what are good ways to help soreness. I know stretching but is that like right before you do the workout, right afterwords, 30 minutes before or after etc? and like should you warm up before stretching?