As you will know if you have read my eBook (here: A Philosophical Approach to Jazz Piano), my concept of the Purposeful Pianist is firmly repeated and enforced. I would now like to firmly repeat and enforce the concept of Purposeful Practice; we know that practice is necessary to pianistic development, but how best to occupy 30 minutes (or hopefully more) of each day on the piano? What takes some people many hours to perfect need only take a few minutes each day, with better results and less frustration.
The trick is not to build a house, it is to master the laying of individual bricks until you have a perfect house.
With this in mind, let's highlight the most important components in piano playing and discuss how best to practice them. My philosophical approach to this subject, as well as life in general, may be unusual to the majority of my readership, but I urge you to read to the end nonetheless.
The keyword here is Purpose. What do you intend to practise for? Why do you practise? Sitting at your piano and merely going up and down major and minor scales at great speed may not be necessary for you; murdering one bar of a particular piece of music may not be necessary for you; repeated notes and playing old repertoire may not be important for you. First of all, question your motives and your intentions, your ambitions and your reasons for dedicating time in your day to practising at all.
Once you have decided upon the aforementioned, Prioritise. If your purpose is to learn lots of songs and not worry about technique so much, dedicate your time to internalising one new song/day. Before long, you will have 25 or more, every month. In less than 6 months, you will be a walking repertoire of music - you may not play any of it very well because you didn't care about technique, but you know lots of songs for your own / your friends' enjoyment and your purpose has been fulfilled. If you would like to become proficient, then you must go into more detail with your priorities.
Generally, the left hand is weaker than the right, and on both hands, the ring and little fingers are weakest. If you just wish to play quite well, up to around Grade 3 or 4 (of 8), trying to improve these weak fingers is of very little significance for you, but getting some of the common major and minor scales into your fingers would be beneficial. Every practice session, absolutely internalise a new major and minor scale, and only that. Do not do anything else. Do not think of anything else. Let's say C, F, G, E flat and B flat are the more common keys for music (especially jazz, and this is a jazz blog primarily, after all), all you need to do is alternate 5 minutes between both hands individually playing up 3 or 4 octaves of the major and minor scale of one of the 5 keys noted above. Do nothing else. By mastering the major and minor scales over 30 minutes, with 1 each day, in 5 days you will have mastered and internalised 10 scales (the major and minor of the 5 most popular keys). Your fingering will be correct or comfortable and you will feel at home in each key... after 5 days. And both of your hands will be as comfortable as each other.
Maybe you would like to go further and study for high-level exam taking; grade 5-8, or even beyond. This is where Prioritising is most important. It is also important on a mental level, away from the piano. Again, my book discusses this in greater detail.
At the piano, you must absolutely dedicate every 30 minute period to one thing, and one thing only. Break down the 30 minute period (of which you could have 2 or 3 or more...) into two 5-minute sections and stick to it without fail. Do not set a goal, simply do the practice you have set. The goals limit your natural progress, and I do not believe they help. If you set a goal, you will feel a pressure to reach that goal and become frustrated if you do not reach it each day. Have a long-term goal, sure, but not every 30 minutes, every day. Just dedicate your time as I have discussed, and your progress will be impossible to follow because it will be so rapid.
At the piano again, give attention to each individual finger and allow it to become an extension of your thoughts, rather than always watching it from your eyes. Elsewhere on this blog, you will find a post about physical performance and internal connection to the outside, but in a nutshell, without trying to be spiritual because that is not the purpose, you must recognise that only your conscious brain says your fingers cannot do something, not your emotions; they do not know how capable your fingers are, so once you begin to focus on and channel the emotional energy from within, during both practice and performance, your dexterity and general ability and touch will improve without any conscious effort. It may sound out of place here, but do trust me.
Away from the piano, practice can also take place. There is a little-known psychological fact which states that the subconscious mind does not know the difference between fantasy and reality. Using this maximally to our benefit as pianists, we are thus able to learn scales and song sections without physically playing. Once a part is internalised, yet we can't seem to bring our fingers to play it physically, spend 30 minutes of absolute concentration, perhaps in bed before sleeping, or when eating lunch on a park bench in the warm sun, playing the parts and feeling the transfer to energy (which is physical electricity from the brain to the finger muscles when you actually play) to your hands. Believe it or not, your ability to play that difficult part will disappear.
In conclusion, simply remember to Prioritise your Purposeful Practice. This will enable you to lay a perfect brick and indirectly, without conscious effort, construct a solid, beautiful, firm and resistant house. I hope you enjoy this metaphor as much as I do.