Hello! I am Mark - Hopefully I can help some of you.
I am currently 16 but I received my 142/150 in grade 8 piano 3 years ago. (I'm now 18.)
I have also acquired a diploma in the piano, along with grade 8 in guitar.
Okay - so if you basically just do as I say here, you're essentially guaranteed a distinction. This initial post might also answer any common questions you have...
I often see questions like 'which grade should I take and when' and stuff, so basically if you follow this, you can take any grade that isn't completely out of reach to you, just as long as you don't be silly and only 'loosely' follow any suggestion that you decide to follow.
How to memorize/learn the Scales.
Well. First off, make sure you learn where the semi tones and tones take place in each scale, for example in any major scale, the semi tones are only between the 3rd and 4th note, and the 7th and 8th (=1st) note of the scale.
Next you'll want to play the scale you're learning a few times slowly.
Once it kind of fits underneath your fingers, the most efficient way to learning them fluently is rhythmic practice. If rhythmic practice is new to you - take note.
Rhythmic practice essentially involves taking something that is in straight quavers or semi quavers (such as scales) and applying dotted rhythms to them so that afterwards, when played normally, they are easier.
A scale would normally be quaver quaver quaver etc...
So practice it first: dotted crochet, quaver, dotted crochet quaver etc...
Next the other way round (often harder): quaver, dotted crochet, quaver, dotted crochet etc...
Then do both rhythms again staccato, then legato again, and finally, straight quaver (normal) rhythm legato. If you follow this, and do it a few times over a few days, the scale will be fluent. Rhythmic practice that also features different articulations is the best form of practice to get any fast or scalic passage fluent. Also coming up with other rhythms will help too!
How to Learn the Pieces
For fast sections, please reread the section above about rhythmic practice.
Turn off your phone when practicing - concentrated practice for 1 minute is better than phone-on-your-mind practice for 10 minutes
Playing pieces from start to finish over and over again is NOT practice. When you sit down at the piano, go to a part of the piece that you know you can't play well, play each hand slowly separately and then play hands together slowly. If need be then go through each bar one at a time until it is fluent. At the end of your allocated practice time for a piece, you can play it through maybe once or twice, but this simply alone is not enough to perfect a piece. Rhythmic practice is very important! Try eyes closed! Try exaggerating the rubato! - Trying things make you think about the piece and therefore help drill concepts of the music into your mind. Oh yeah - Rhythmic practice.
I dare you to get a pen and paper right now and right down all the dynamics of each section and any expression markings or tempo markings of a piece - once you fail at this, go through the music AWAY from the piano and memorize any markings given by the composer.
If you are playing any Bach then also make sure you know where the themes are.
People doing lower grades also tend to make the mistake of repeating the same rubato ideas throughout a piece - don't bore the examiner, be creative.
Regarding the Aural
Don't complain about how you can't sing. Examiners. Don't. Care.
Your voice is fine. Examiners know which pitch you meant to sing if you sing slightly out of tune, and no marks are given for quality of voice.
(Sometimes you'll be given the option to either sing back the melody or play it on the piano, always choose to sing.)
Maybe do a little practice with your piano teacher or basically anyone.. The aural sections aren't hard and really you shouldn't worry about them
How much practice do I need to do? Which Grade should I take?
Here's how it works. If you want distinctions. Here.
Grades 1-3: 10 minutes of concentrated practice a day
Grades 4-6: 20-30 minutes of concentrated practice a day
Grades 7-8 30-60 minutes of concentrated practice a day.
Seriously TURN OFF YOUR PHONE before you sit down at the piano.
Start off with scales. Play 2 or 3 of the ones specified by the grade and make sure you go through the rhythmic practice concepts I listed above - this will stop your time from being wasted. Don't spend more than 10 minutes on scales, preferably only 5. If you're doing grades 1-5 then simply playing through your pieces once a day hands separately each hand at a time, and then playing through each ones hand together first slowly and then up to speed, can simply be enough practice. The lower grades don't require much dedication to practice methods other than just playing through.
Grades 6-8: Do not just play through your pieces. Spend at least 10 minutes repairing any bars that you can't play and just make sure all sections are as fluent as each other. One good use of your practice time is to sit at a desk and just write down every single fingering that you play on a photocopied version of the piece - do not underestimate this.
So after your 5 minutes of scales, and then 10 minutes per piece of concentrated practice finish off by playing through your favorite piece one last time or by going online and finding some fun sight reading.
If you have any questions or would like some help with specific sections of any piece, feel free to ask.
Thanks for reading!
if you take anything away from this post, please be rhythmic practice and practice featuring different kinds of articulation. This really helps with accuracy, memory and fluency of anything you're playing.
1/27/2019 - Edited (most points were not edited at all.)