Watch the weather report. Warm days on the South Fork will greatly increase your chance to catch trout. Rubberlegs have been working really well. The fish are hanging out in the tailouts of riffles and deep holes. Be sure to bring your midge patterns and use them when you see noses on the surface.
During the winter the boat ramps do not get maintained for snow. It is easier to leave the boat at home and wade the South Fork during this time of the year. Acces is really good for wading this time of year. Consider Hiese Bridge, Twinn Bridges, Spring Creek Boat Ramp, Byington Boat Ramp, Wolf Flats and the Great Feader Canal. All of these locations offer pucblic acces to the river, and you can wade and fish the river very easily from these locations. Remember to use common sense and be extra cautious while fishing during the winter.