Inability to play on all keys would cost you a whole lot as a Pianist because it limits you beyond measure.
1. Delete the transpose button
The best trainers would tell you that always using the transpose button is your greatest enemy if you want to learn how to play on all keys. If you are serious with your career as a pianist, you have to “delete the transpose button”. -imagine and behave like it doesn’t exist.
2. Set a schedule to learn each key
It would be effective if you schedule a period of time to master each key on the keyboard that you’re not too familiar with. For example, you can dedicate 2 weeks to learning key F, then another 2 weeks in learning key D etc.
3. Learn the keys in an appropriate order
There are order of sharps and flats and it is important you learn how to play following this order because it is a very systematic and organized way of learning as you get to see that the sharps and flats on each key is a build up on the other. The sharps are arranged in a cycle of 5ths while the flats are in a cycle of 4ths.
4. Score songs in their original keys
While playing as musician there is always the temptation to always want to sound very good even though you’re not skilful. Therefore, we always tend to transpose to cover up for our inadequacy to play on all keys. Instead of transposing and playing on the key that you’re comfortable for songs which were originally arranged in another key, try to score/transcribe songs you’re meant to perform in their original keys. While you’re doing this, you’re gaining mastery in that key.
You could also take a set list of ”Praise and worship songs” and practice them on each new key you’re learning.
5. Move from known to unknown
When learning a new key, take your time to practice the concepts you already know and then gradually begin to learn the new concepts on the new key. If not, frustration would set in.