Regarding “Always do your best…?”, I think you should never consider you did your best.
You should aim for doing things the right way, you should aim for perfection.
If perfection means doing things 80%, that’s fine. If it means just scratching the surface, doing 10%, it’s OK also.
But, once the task has been done, if you look back at what you did and say “Hey, I’ve done my best”, you’ll never wish to grow.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” ― George Bernard Shaw, Man and Superman
I don’t think I did anything perfect. I did get some things right, but perfect – no. There’s always room for more.
Why do I say “you can do everything even better!”?
Because there are multiple aspects of any activity.
A product, a service, an entity – everything has multiple aspects on which it can be improved. I don’t think I consider that anything’s perfect in this world.