Let's get straight to it: the gear you select should always be appropriate for the speed you are travelling, as well as the road, weather and traffic conditions.
Ride in a gear that provides enough torque for instant acceleration without the need to change down to get it. The lower the gear the greater the torque available for acceleration and engine braking, but the lower the road speed possible.
Being in the right gear, close to maximum torque, is essential for overtaking. Make sure you’ve got the right gear selected, so you’re ready to overtake with maximum acceleration when the opportunity is clear.
Changing up or down, maintain pressure on the gear lever until the clutch has been released to minimise the likelihood of selecting false-neutrals and losing drive. If a false-neutral is entered, change up a gear. Changing down, you might select a lower gear than intended, risking rear-wheel lock-up and a possible skid.
On older bikes, the gear lever can be on the right hand side. On some, the change direction can be the opposite of current bikes. Be very careful when borrowing a bike.
If selecting first gear from neutral is noisy, holding the clutch in and blipping the throttle can help free the clutch and make it smoother. Allow the revs to drop back to idle before engaging gear. Always keep the front brake on until you’re ready to pull away.