With respect to comparing oneself with other people, "Better at, not better than" -- can't remember when this was given, want to say 8th grade from some counselor interviewing me for something or another (career guidance? I remember him asking me about a phrase I liked back then, "Through knowledge, power"). I don't really agree , but I mulled over it then and still remember it, and it's not terrible as far as generic advice goes, especially if it can help someone avoid a superiority complex, which I'm sure back then I looked like I might develop.

A HS teacher had "Pay yourself first", which I still like, and is especially useful for people who might otherwise help others too much at their own expense (and ability to help a lot more in the future).

I think the real lasting advice that I still think about and would like to more perfectly follow is ch 9 of the tao te ching. One translation goes:

    Fill your bowl to the brim
    and it will spill.
    Keep sharpening your knife
    and it will blunt.
    Chase after money and security
    and your heart will never unclench.
    Care about people's approval
    and you will be their prisoner.
    Do your work, then step back.
    The only path to serenity.

Another translation:

    Brim-fill the bowl,
    it’ll spill over.
    Keep sharpening the blade,
    you’ll soon blunt it.
    Nobody can protect
    a house full of gold and jade.
    Wealth, status, pride,
    are their own ruin.
    To do good, work well, and lie low
    is the way of the blessing.