The recommended distance when passing a cyclist is 1.5m.
If you are passing a cyclist who is riding next to a line of parked cars, they will need to ride further out into the lane to protect themselves against people opening car doors.
When you are following a cyclist and are about to overtake, look at the road ahead. Is there a pothole or drain the cyclist might need to avoid? Is there any debris on the road that the cyclist could swerve to miss, such as broken glass?
If there are strong crosswinds these can cause the cyclist to wobble as they move out of wind shadows like a large parked vehicle (e.g. a bus) and buildings. If you are driving a large, long vehicle, you could create a wind shadow as you overtake them.
If you are driving a longer vehicle be sure that you have completely overtaken the cyclist before you pull back in. Be careful of your wing mirrors - clipping a cyclist with your mirror could cause them to fall under your wheels. If you are driving a car with a trailer, be aware that trailers can be up to 2.5m wide whereas your car might only be 1.9m wide, and that means the trailer will be 30cm wider each side than your car.
If you are turning left up ahead, do you have time to get past the cyclist before you turn? Sometimes it's better just to wait behind the cyclist and turn behind them.