My instructors always said to pop the clutch a bit on every gear change - it prevents the gears from crunching or entering in to a false gear or false neutral. So I will always pull clutch, drop a gear, let clutch out, clutch back in, gear down etc for each gear. One other bit of advice is to blip the throttle just before you change down whilst the clutch is in. Makes the change a lot smoother when letting the clutch out as the revs are more in line with the road speed of the next gear