Hello,
With Major scales, you have a fingering pattern that you can follow, So ascending doing two octaves it is: - 3, 4, 3, 5. so descending, it will be the same pattern, but obviously, the other way around!
An example of what I mean by this is: - (basing on c major two octaves...)
RIGHT HAND: - C D E F G A B C D E F G A B C (THIS IS ASCENDING)
1 2 3 1 2 3 4 1 2 3 1 2 3 4 5
DESCENDING: - C B A G F E D C B A G F E D C
5 4 3 2 1 3 2 1 4 3 2 1 3 2 1
Your also find that this fingering pattern is the same for minor harmonic scales, like d minor, g minor and a minor.
Its also the same pattern for contrary motion scales.
Hope you find this useful.