..and last but by no means least. Slower retrieved always worked better for me (Sometimes I would mix it up by doing the slow retrieve with an odd twitch of the rod tip every now and then). Experimenting with retrieve rate, jerks of the rod tip and different presentations can make a difference when the fishing appears to be slow.
Yes, definetly change up your retrieve before switching up lures or flies.
It may be colour but if it may be the retrieve.
Vary your retrieve several times before you tie on something different when not getting any action.
And yes, it's not just the colour pink as pointed out above.
Pink, blue, purple, chartreuse,...... and combinations of these work well also.