A work ill done must be done twice done. 
一事做糟，两次重搞。

If you would have a thing well done, do it yourself. 
想把事情做得好，就得亲自动手搞。

Whatever is worth doing at all is worth doing well. 
凡是值得做的事情，就值得做好。

Affairs that are done by due degrees are soon ended. 
按部就班，事情很快就做完。

In for a penny, in for a pound. 
事情既已开头，就要坚持到底。

Never do things by halves. 
做事切忌半途而废。

Finished labours are pleasant. 
完成工作是一乐。

Work makes the workman. 
勤工出巧匠。

The used key is always bright. 
常用的钥匙常光亮。

Drawn wells are seldom dry. 
常用的井不会干。