1. Study sickness while you are well. 
2. If you wish for peace, be prepared for war.
3. You can't make an omelette without breaking eggs.
4. If you want knwledge, you must toil for it.
5. You cannot judge a tree by its bark.
6. You can’t touch pitch without being defiled.
7. I tell you hopeless grief is passionless.
8. Grasp the nettle and it won't sting you.
9. You win some, you lose some.
10. You can't have your cake and eat it.
11. You may delay, but time will not. Benjamin Franklin
12. You have no goats, and yet you sell kids.
13. If you command wisely, you'll be obeyed cheerfully. Thomas Fuller
14. Never trouble trouble till trouble troubles you.
15. Don't halloo till you are out of the wood.
16. Never (or Don't) trouble trouble till trouble troulbes you.
17. When you are at Rome, do as Rome does.
18. You must not pledge your own health.
19. Learn to say before you sing.
20. Try your friend ere you trust him.
21. Better ask twice than lose you way once.
22. You catch more flies with honey than with vinegar.
23. You cannot clap with one hand.
24. If you want peace[sentencedict.com], prepare for war.
25. By writing you learn to write.
26. Would you know your daughter, see her in company.
27. If you swear you will catch no fish.
28. Improve your time and your time will improve you.
29. Forget not that you are a man.
30. Catch the bear before you sell his skin.