Ask Grandpa for a dollar. When he gives you a dollar, get up in his lap, hug him, and then sit there for a minute telling him what you'll spend the dollar on. Every time he sees you from then on he'll happily pay another dollar for that same interaction. Bonus points if you say you'll spend it on Grandma.

Eat the cookie now. Saving might sound like the smart thing to do, but then it gets stale.

Parent of 3yo (so the last three years make up for the decade plus I miss from the question).

If you don’t clean up pieces of your toys are getting lost. It’s not a threat, I will even help you look, but we have already lost some pieces in the mess…

Money is bad and you should be afraid of it

The time-value of money beats any possible investment opportunity. Separate account (NOT a trump account, unless you want it stolen or fucked with later) that the kid doesn’t have control of.

Big holidays + birthdays when you say to yourself “ugh this kid has TOO many toys!” then what you do is you drop the largest chunk into that account and just buy the S&P500 and let it cook.

When that kid is 18 or 21 or 25 they’ll have a very respectable chunk waiting for them. Read more about boglehead finance strategy if you’re interested.

Half for me, half for now. Every check, allowance, paycheck gets split. Half goes into savings the other half they can keep and use on whatever.

This teaches about saving, to some degree taxes, and the power of compound interest without needing to understand the math.

Second suggestion is the old adage: the best time to plant a tree was 20 years ago, the second best is today.

Applies to retirement and education saving. Also applies to actual trees and climate change mitigation.

Third if you are waiting for someone to do something about "it" you are that someone, might as well get started.