it is a wishes, directed to someone, intended to wish someone very best result, while he is going to do sth.
No because the meaning is obvious: you are trying your best at something.
Show your better side, be the best you can be
The literal meaning would be that you have one foot that is "the best" and you're tossing it out ahead of you.
"To be" is not an idiom - it's a verb.
It just means your best - the image is of you making sure that your best is totally level and perfect in appearance.
It means you did your best and were honorable; you didn't cheat or anything.
Pest is not an idiom. It's a word.
The idiom "apple shiner" means the teacher's pet.
The meaning of the idiom in the pink of health means being in good health.
The idiom means impress someone is egg on
It's not an idiom - to cope means to deal with, or to handle
"Old hand" is an idiom meaning having lots of experience.