Your search for "Whatever is worth doing at all is worth doing well. - Lord Chesterfield 1694 - 1773" revealed the following:

Modesty is the only sure bait when you angle for praise. - Lord Chesterfield 1694 - 1773 - RW-22.6

Modesty is the only sure bait when you angle for praise. - Lord Chesterfield 1694 - 1773 - Drink Wisely in MugWisdom - Ceramic 11oz cup - MW-22.6

RW-6.8 - Knowledge is of no value unless you put it into practice. - Anton Chekhov 1860 - 1904