Another tip, if it helps. When you are slowing to a stop you might usually freewheel to a halt and therefore find yourself in the wrong gear for departure. As you are slowing you can slowly spin the cranks to change down, without having to actually drive the bike forward. You'll still be effectively freewheeling but just turning the cranks enough to make the gear change. I find this useful if, for example, approaching a t-junction where I know I will have to slow and give way but may be able to ride through if it's clear.