You have to play the piano ultimately as if you invented piano playing. And indeed one has to re-invent piano playing for one self. One has to wield ones art like a holy flaming sword.
Having a brilliant balance, a sonorous tone, an orchestra at your finger tips ... is a matter of creating a sound you imagine and want to hear, a desired sound.
The end of a piece must be a confirming statement or a tender good-bye, not an rustled apology or a rushed IED.
In every solar system in the galaxy is a range around the sun within which the ideal distance and trajectory for a life sustaining environment is provided. Astronomers and astrobiologists term that range the Habitat- or Life Zone, colloquially the "Goldilocks Zone", the "just right" distance from the sun. Not surprisingly our planet is in the Goldilocks Zone around our star - 2% further out and global glaciation would envelop the planet.
When you warm up before a performance, don't just warm up your fingers: warm up your ears, your musical mind, your artistic soul!
When you rehearse alone before a concert, you can and perhaps should play at a slower tempo, but under no circumstances should you play with diminished dynamics. Loud and expressive you must rehearse your performance repertoire!
When we have a melody in octaves, usually we'd lead with the high and sometimes with the lower voice. But try to sing the octave as a compound sound like strings can and do.
Fingerings often subdivide in different places in parallel passages ~ e.g. scales with both hands over 4 octaves, the howling wind over the graves in the last movement of Chopin’s Bb-minor sonata, the playful wind over the steppe in the last movement of Tchaikovsky’s concerto in the same key, and such. It is the performer's right to choose which hand to give leadership to.
If it is challenging to play difficult parallel passages together fast, one should not only lead with the left hand, but group (subdivide) by the left hand. The right choice then is to master and obey the left.
There is one crucial technical misconception: the supposed inferiority of the 4th finger. The truth is that only the lifting capabilities of the ring finger are limited due to the connection of the three outer finger extension tendons (extensor digitorum communis).
The muscles responsible for lowering the fingers (lumbricalis) are not connected in any way and therefore unrestricted. If the finger lies relaxed on the keys and is activated without continuous tension - i.e. relaxed immediately after contact - the up lift of the key provides half the effort to lift the finger.