When you are working long stretches in a single colour in stranded colourwork, it creates a very long 'float' across the back of the stitches with the second colour.
The best way of dealing with this is by 'trapping' that long float at the center of the stitches so that you don't have a very long loop that can get caught at the back of your work.
Steps to trap left hand float:
- Insert right needle into next stitch.
- Lift left hand yarn over tip.
- Knit yarn from right hand, holding left hand yarn above.