The advice I was given which I think is pretty damn good advice:
(As said by everyone else) Assume every other road user is an idiot, you'll be right a surprising amount of the time.
When you're on a road and see someone waiting to join that road (from a junction etc.) take your foot off the accelerator and cover the break incase they don't see you and pull out.
When looking to see if someone is going to pull out or not, the best way to judge whether they're moving or not is by looking at the wheels as you'll see the spokes turning, much more noticeable than seeing the whole car move a few inches.
Don't ever switch off whilst driving, this is how I hit the curb of a traffic calming measure, blowing up 2 tyres and setting off an airbag, just from lack of attention a month into driving when I thought I'd got the hang of it.
I've never really understood how peer pressure works as it doesn't bother me, but don't go racing your mates or get encouraged to drive fast etc.
Finally, the speed limit isn't a target. You should always drive to the limits of the road and conditions. It may be national speed limit but that doesn't mean you can do 60 around every bend, or in fact any bend that may be on that road. Especially in the wet.
There are my words of wisdom. Seems weird coming from an 18 year old who's been driving just under a year but I think most people will agree with that advice. Best of luck mate, enjoy driving on your own, it's ace.