About wrist etc. movement

[xavura]

Is there any material on the internet that I could read, or preferably videos I could watch, about correct and incorrect movement of the fingers/wrist/arms and such?

I've played for a long time (~20 years) but I've never had proper piano lessons and I've noticed that when I play more advanced pieces, especially 7/8/8+ ones that I over time feel (sometimes extreme) pain, especially in the wrists.

There must be something wrong with my technique?

[hmpiano]

There are hundreds of web sites.  You really need a teacher though.  Here's just one of them: https://www.pianocareer.com/

[xavura]

Yeah I should have searched before asking, I managed to find a few but thanks for the link.

I'm getting a teacher soon (mainly with an aim towards doing the grades) so I will ask them about this as well.