Learn the Highway Code - it's not just for cars!
Signs and traffic lights apply to cyclists' bikes as well as other vehicles, and you have to stay off pavements and paths unless signs specifically say you're allowed.
If you can, it's probably better to use cycle lanes and paths, and never ride more than two side-by-side.
On narrow or busy roads, or going around bends, stay in single file.
And don't ride too closely behind any other vehicle.