You are in control of a one ton bullet - in fact it's worse than a bullet in that you can kill several people in one go including yourself. Always consider if your speed is appropriate taking into account the following:
A vehicle is at its most stable when driving at a constant speed in a straight line.
Conversely braking going round a bend it is at its most unstable. Add to that a wet, muddy or icy road and you are seriously at risk.
Wind and or a bad road surface and or camber can also destabilise your vehicle.
Distance is an important factor in safety. This has to be considered in relation to other road users - meaning choose the middle ground or slow down if necessary, especially with the unpredictable - animals, children, cyclists and the inebriated.
Give pedestrians, animals and cyclists a few extra feet even if on the pavement.
Your vision is restricted when you drive too close to the vehicle in front putting you and it in danger from unexpected actions by the front vehicle.
You have more scope to take evasive action if, apart from steering, you only do one thing at a time.
e.g. to take a side turning, mirror, signal, brake, stop braking, change gear and then turn with both hands on the wheel. This makes you think ahead and plan early.
Of course this is easier with an automatic but you still need to be travelling at an appropriate constant speed as you turn, be it a corner or a bend - gentle application of power as you come out of the bend improves vehicle stability.
Treat roundabouts as a clock - you enter at 6 pm. If taking the first exit signal left as you enter the roundabout. If your exit is after 12 noon signal right. In all cases signal left as you align with the exit before the one you intend to take. With more than one lane enter in nearside lane for up to 12 noon.
Overtaking is the most dangerous manoeuvre of all as there is more to think about and judge. The speed of each vehicle combine in a head-on collision - two vehicles travelling towards each other at 30 mph collide at 60 mph - ouch.
Your Aorta will rupture if you stop at 30 mph. An airbag might just save you at this speed. If you survive above this, its because you slowed down rapidly rather than stopped dead.
Young drivers - passing a test requires only a basic driving ability. Judgement is learnt over time - i.e. with experience. Think about all the above when you increase your speed above the 30 you have got used to. Don't allow your friends to dictate how you drive.