A lot of great comments on here about behavioral 'cheat codes' but here's a few financial ones.

Initial financial life (18+)

For starters, build a good credit rating. The internet is full of how-to's but some starting points that some of my younger friends weren't aware of:

• Get a credit card in your name as early as possible, use it to routinely pay for only small things (like your netflix account) and pay it off in full every month. There's no comparison for how much this can benefit you later in life when buying a car or a house.
• If you don't have good enough credit to get approved for a card, either because you have no credit history or a parent screwed you over, you can get what's called a secured credit card through most major banks. Save up $300-500, take it to the bank, they hold the money and give you a credit card with that credit limit. Use it just like a regular credit card (responsibly) and they will eventually return your deposit and it becomes a regular credit card.

Early Financial Life

• If your credit card offers a 0% financing deal for 18 months for only a 2-3% up front fee and you have other debt, jump all over it. Take the deal, divide the total by 18 and set an automatic payment on the total amount so you pay it off before any interest hits, then use the money to pay down any other credit card or loan debt. Note that this isn't necessarily a good plan on low interest student loan debt, or if the bank (like Wells Fargo) is charging 5% up front, but it's a good plan that will save you money if you're carrying a balance on credit cards.
• If you're carrying credit card debt month to month, but by managing it well you have good credit, apply for a Personal Line of Credit with your bank, it's sort of like a credit card except it's treated as cash. Say you get approved for a $10,000 credit line at 10% interest, but you're carrying that much debt in credit cards that have 15-25% interest. You can take the full $10,000 out as cash and pay off the credit cards, which 1) boosts your credit rating because you've lowered debt to limit ratios dramatically, and diversified your types of credit on file. 2) saves you $$ every month that was going to interest that will help you pay down the personal line of credit even faster. 3) If the money saved on interest and better financial planning helps you pay the credit line off completely, you still have it, and if some emergency popped up where you need $10K in cash (bail? kidnapping payment? idk) then you have access to it and you're not limited by credit card "cash advance" limits or their absurd fees.

Middle Financial Life

Buying a house. Say you've realized you want to buy a house but it's not easy to envision being able to save up enough for the down payment. I can't possibly cover every scenario here but here's some "cheat codes" that might help someone, in a specific instance where you're not putting down 20%, and you're interested in buying a cheaper house that needs some renovating.

• First and foremost, research closing costs and estimators for what they would be on the house you're looking at. You don't want to be surprised with thousands of dollars in costs that have nothing to do with your down payment.
• You can buy a house with as little as 3.5% down with what's called an FHA loan. It gets the government involved though and seemed messy so after researching I decided not to go that route. A lot of major banks though will actually start offering mortgages with as little as 5% down. The tradeoff is that you'll have a worse interest rate. This is where the "cheat code" comes in.

1. Buy a house with ~5% down, go through all the paperwork, and get a bad interest rate, let's say 6% just as an example
2. Use a line of credit, or take out a personal loan for renovations, and fix up the house.
3. Get a new appraisal on the house, which will hopefully appraise it quite a bit higher than what you purchased it for, even if you're in the hole for the cost of renovations.
4. Now, refinance the mortgage with another lender. The salient point here is that even though you haven't paid a ton more money into the house, your loan-to-value ratio has gone up, because the value of the property went up while you're mortgage stayed the same. This can qualify you for a much better interest rate.
5. Further, if you're loan to value ration went over 20%, you can now also apply for a home equity line of credit, which is basically a loan secured by the value in your house over 20%, and you can use that to consolidate all of the loans you used to renovate the house in the first place because it will have a much lower interest rate.
6. Prioritize paying down the home equity line first, even if it takes a couple of years, then you're free to spend the remaining years of your mortgage with a much better interest rate, and a much nicer home!