We remind that headlights and rearlights as well as the use of reflecting suspenders are obligatory in tunnels, even considering that most of these are illuminated.
Give your bike a regular checkup, especially if you've had it for years.
Be seen: you must wear a high vis jacket (or sash) in tunnels and on country roads after sunset.
Always wear your helmet.
Make sure your front and rear lights are working.
Put out your arm to give advance warning of your intention to change position and before you do anything, check there are no vehicles coming up behind you.
Don't use headphones or your mobile phone handsfree kit: you need all your concentration on the road!
Obey the road signs: stop at traffic lights and don't ride on the wrong side of the road.
If you are cycling in a group, always go in single file.
You've got a bell: use it to let pedestrians know you're there. Don't ride on footpaths. If you have to then get off and push your bike.
If there are cycle paths use them. It's your safety that's at stake and the rules of the road say you must.