You need your beauty sleep.
How many parents try to get their children to go to bed using this maxim?  Lack of sleep is supposed to lead to shadows around the eyes.

Beauty is only skin deep
is an expression I have known from childhood.  Character is more important than appearance.  I later came across it paired with:
but ugly goes clear to the bone!

You never know who’s watching you.
This is true.  In small communities it is important to watch your step.  Also the number of people I have heard about meeting people they know in far-flung places is truly amazing.

What’s done is done.
This is another saying along the lines of it’s no use crying over spilt milk.

Live and learn is often said after a mistake has been made.

Live and let live!
This instruction has overtones of mind your own business!  It was famously adapted for the title of a James Bond film – Live and let die!

Don’t cross your bridges before you come to them.
People often worry needlessly about things which might happen in the future.  Alternately they might make plans which depend on many external factors.  In either case they might be looking too far ahead.

Don’t burn your bridges they might be needed for a retreat.  This is a metaphor for not acting in a way which would reduce your options unnecessarily.

Pull yourself together!
This is good advice to a child who has been crying over something and nothing.  It is no help at all to anyone who has problems with their mental health.

It’s always the way.
This is a popular saying about how events have worked out.

You need to broaden your horizons
is advice against becoming insular or parochial.

Travel broadens the mind.
This is an old saying.  It remains true that leaving your locality opens up new experiences and information.  Nowadays surfing the net or watching TV provide images of far away places.  Travellers generally agree that there is nothing like seeing for yourself.

Your wish is my command.
The genie in Aladdin says this as far as I remember.  My Mum used to say it to us when we requested her practical help.

To be on the safe side is to err on the side of caution.

Margin of error is perhaps the extra safety allowance.

The brink of disaster is somewhere to be rescued from.  A brink is an edge.

Forgive and forget!
Neither of these is easy to do. Is the forgetting essential as long as you do not nurse a grudge?

Matthew 6:7-15