Good Advice

For a long time I've been interested in short sayings that provide good advice. Aristotle in his Rhetoric termed them "maxims," short sayings that offer wisdom and a sense of meaning or direction to our lives. Later on, Emerson utilized aphorisms, which are essentially maxims.

I have some maxims in mind that probably shouldn't be presented in this forum ("beer before liquor, never sicker," and we can regress from there), but one I've always found value in is a statement that Virg, my father, said that my grandfather liked to say: "A wise man will change his mind, but a fool never will." 

Also, the Southernism of "That whip don't mean too much when the mule ain't got a chance" resonates with me since I'm a teacher.

I also like the weird saying that some people in the South use when food is so dang good that it incites feelings that create insanity: "So good it'll make you slap your mother." 

So what are sayings/maxims that you find valuable or interesting?