1. People who live in glass houses (shouldn't throw stones).

This is something that you say which means people should not criticize other people for faults that they have themselves 

2. The first step is always the hardest

Everything is easier once you have already started; it’s getting started that is the hardest part.

3. Walls have ears.

This is something that you say in order to warn someone to be careful about what they say because someone else may be listening 

4. When/While the cat's away (the mice will play).

This is something that you say which means that when the person in authority is absent, people may not do what they should do 

5. Time is money.

If we don't use our working time to earn money, we are in effect losing money.

6. While there's life there's hope.

As long as someone who is sick is still alive or something that is not doing well is still surviving, there is hope for a recovery.

7. Sleep is the best medicine

Getting enough sleep is better for your physical and mental health than taking medicine.

8. The grass is always greener (on the other side of the fence).

This is something that you say which means that other people always seem to be in a better situation than you, although this may not be true.