Finding the right instructor for you - I would always recommend paying for 2-3 lessons instead of a block right at the beginning of your lessons. When you first meet an instructor, it's hard to tell if you're going to like their teaching style. It definitely takes a few lessons to figure out if you're going to get along! As an example, my first driving instructor made inappropriate jokes and turned the radio up really loudly on my first lesson.. needless to say, I changed instructor! I really didn't feel comfortable with the radio playing as I fearfully drove a car for the first time in my life....
Start Early - I really, really wish I had started my lessons when I was seventeen. I was too scared to call up a random person I didn't know and ask them about starting... Can you believe I used to be such a baby?! I ended up starting them at 18 and did them for around 13 lessons before I went off to uni - long story short, it was expensive and as soon as I got to uni, I couldn't afford to continue with 2 hour lessons every week, which was the way I found it easiest to learn (an hour flew by far too quickly) I do wish I would have booked lessons online back then, or at least arrange a call back. I guess I never looked into it properly! If you're a bit like seventeen year old me, you can actually do that on a website called called Book Learn Pass. They allow you to book lessons online and do the leg work for you in finding an instructor. Easy-peasy! They also have a lot of information regarding lessons/theory tests and practical tips on their site, so be sure to head on over and take a look.
Learning on the go - Everyone learns in different ways obviously, but some of the things I found most helpful were asking the 'stupid' questions during my driving lessons... and I mean stuff like 'why can they go ahead of me from that lane? Why can't I cut in front of the granny, I've had three lessons now? I'm practically a boy racer..?' .. Kidding, but you know the things you're too scared to ask? They're always available online for you to look up and research, and remember, your instructor won't think you're stupid for asking - they've likely seen it all before! And hey, when you're paying around £20-30 an hour.. ask away on that rate!
Be aware - Probably an obvious one, but sometimes it can be hard to tell when you're being taken for a ride. Literally. My first instructor spent an entire hour and a half of my first lesson explaining where parts of the car were and did most of the driving himself. I ended up behind the wheel for about half an hour (probably less...) of my first 2 hour lesson.. not cool. Most instructors are really great and want to help you pass quickly so that you recommend them to your friends.. but some will end up making you need 50 hours of lessons. (The average is around 30/35 before you can pass for most people).