Rule No. 1: Pay yourself first. Put the first 10 percent of your earnings into savings for the future. The most painless way to do this might be with a 401(k) plan at work. Since your paycheck will be a few percent less than you would have, otherwise, you will grow not to miss it at all. Put the maximum that the company will match. If you have more than that (say 4 percent of the 10), then put that 4 percent into the maximum you can invest in an IRA - regular or ROTH, you decide. If you still have some left, put that little bit extra back toward your 401(k) or put it toward your emergency fund.
Rule No. 2: You need an emergency fund of at least 6 to 12 months, depending on your situation. If your talents are in high demand, you might only need 6 months of savings. For anything less than that, shoot for 9 to 12 months. Build that emergency savings account.
Rule No. 3: Of your 401(k) or IRA accounts, invest in Exchange Traded Funds (ETF) in a place where you do not have to pay for such trades or at least not much. Even $5 per trade is too much.
Rule No. 4: Set your investments the way you feel comfortable. If you are a risk taker, buy stock-based ETFs. If you are shy when it comes to risk, buy bond-based ETFs or CDs or such. You are probably somewhere between, so decide on a reasonable mix and buy according to your comfortable mix.
Rule No. 5: Keep pouring the percentages you have chosen into the investments every month, but otherwise Leave it alone! Keep sending in the money to buy more, but don't just trade. Trading will eat you up! Invest for the long term. Keep buying the same shares. That will let you use dollar-cost-averaging. When prices are down, you will buy more shares. When prices are up, you will buy fewer shares. Over time, you will maximize your shares by paying the average price per share.
Rule No. 6: As your income increases, up your investments by at least half of the increases you receive through raises or changing jobs. If you change jobs, be sure to ROLL OVER your retirement accounts with the company directly into an IRA or the 401(k) plan at the new job and reinvest as appropriate for you.
Rule No. 7: When you are younger and your family is depending on you for support, get Term Life Insurance to give them a boost in case you don't make it. Granted, this is for your spouse's retirement, not yours. Remember, tomorrow is not promised to any of us. I suggest a 10-year level term. That means that you pay the same amount per month for 10 years and the insurance amount stays the same during that time. Be sure it is Term Life Insurance. Whole life, Universal Life, and other types of insurance cost you more for less coverage over the long haul.
Rule No. 8: If your term life expires, reconsider your situation. You might still have little ones at home, a hefty mortgage, car payments, and so on. A new policy will cost more than it did, but still get only Term Life, whether you renew with the current insurance company or shop around and find a better deal with someone else. As you reconsider, be sure to alter the coverage amount to meet your family's expenses for a few years in case you don't live until two days after you sign the policy.
Rule No. 9: If you exhaust all your maximums for tax-advantaged investments for your future, put any further surplus into other investments, from savings accounts (CDs?) on up to other ETFs of stocks, bonds, or whatever.
Rule No. 10: Pay your bills. If you have debts, pay extra on the highest interest first, minimums on all the rest. As you pay off the top one, put every dollar of that toward the next highest interest debt and each in its turn until you pay off all debts.
Rule No. 11: Buy food.
Rule No. 12: Hopefully, you can figure out the rest.
I hope she is putting it into Roth 401-K. I think taxes will be a lot higher when she gets older. It's better to pay tax now if she plans on saving a lot in that 401-K. When taking Social Security, you pay up to 85% of your (normal) tax on that SS plus you get saddled with Medicare costs that are quite high if you are in the upper incomes.
Having been in the retirement benefit business administering Defined Contribution Plans (DC) and Defined Benefit Plans (DB) with Social Security integration formulas as well as complying with Federal Regs. for over 30 years, I know the devil well. As you probably know, the three legged stool concept has changed or evolved over time to perhaps a two legged stool which is wobbly. Initially, the three legged concept identified three sources of retirement income with "income" being the key word (SS, Company pension-DB, and personal savings). Depending on age and service factors, SS and DB provided 60% to 70% of one's pre-retirement income. Due to the reduction, freeze, and/or termination of DB in the private sector, most folks in the private sector are depending upon SS for retirement income and perhaps some sort of withdrawal/distribution strategy from DC including IRAs and other personal investments/savings. As we know, many folks are not investing/saving for retirement to the extent that they need to. If I recall correctly, Fidelity came out with a formula/computer program that offered how to obtain certain percentages (30% to 40%) of pre-retirement income by investing certain amounts of money (i.e.,15% to 20% of pay) over time at reasonable rates of return (i.e., 6% to 7%). In other words, developing future values and distribution strategies for average life expectancy or longer if one elected to establish longer distribution timelines. Essentially, it was linear mathematics. I am not sure how successful that effort was because most folks view DC and IRAs as savings accounts not sources of lifetime income. Although SS and a DB provide monthly income, they are separate sources of income. It should be noted that folks do not have any contractual rights to receive SS payments. This has been already addressed by the Supreme Court in 1960 (see Fleming vs. Nestor). Payments under SS are not property rights. Whereas participants in DB (private sector) have rights as well as protection via federal law (ERISA) and insurance with the Pension Benefit Guarantee Corporation (PBGC). The public sector is not governed by ERISA or PBGC.
I agree that a four legged stool is better than a three legged stool. However, I cannot think of what the fourth source of retirement income would be. Some folks may offer various investments (micro concept) which are really an accumulation of personal investment/savings on the macro concept of the third leg. As you know, in the private sector, Defined Contribution Plans (DC) have replaced a substantial portion of Defined Benefit Plans (DB) and many folks do not use their DC values or even a portion of their value at retirement to create lifetime income. I will use the term, annuitization, which is wherein folks can develop income streams, (vary over time), to replace the monthly payments from a DB. Some folks confuse annuitization with the product that life insurance companies sell called annuity contracts. For folks not savvy with money management, perhaps buying an annuity contract with some portion of their DC value may be the appropriate strategy. Congress has already addressed this strategy by adding language to provide for Qualified Longevity Annuity Contracts (QLAC) for DC. At any rate, you indicate a lower risk strategy by using T Bonds (long treasuries?) versus T notes (10 year or less), CDs (FDIC), and money market funds (not FDIC, but $1.00 NAV) which is a great strategy especially after retirement when you need to protect principal. We have seen an increase in the T markets, more so with the notes than the long treasury bonds, due to concerns about inflation. The only comment I can state with any certainty is "don't fight the Fed". The Fed has temporarily backed off purchasing billions of Treasuries which means the largest purchaser of Treasuries is not bidding up prices and driving rates lower. Based on Chairman Powell's recent update, this may change in the near future. Although I don't have a crystal ball, the Fed may be ready to sell some paper and need higher interest rates to attract investors including China and Japan. I believe both countries own $1 Trillion each. The Fed needs to raise some money to finance the spending efforts of the current administration. This may be an opportunity for obtaining a little more safe guaranteed yield over the next few months if you are laddering. Or you can trade the T bonds and/or notes to capture any appreciation should rates decrease. My advice is to listen carefully to Chairman Powell and what direction the Fed is going. Forget about bank CDs. The banks do not need to compete for deposits. Same for money market funds. If you are referring to the economy growing at 7% plus or minus, I would pray for 4%, and accept 2% to 3% as a positive. The Labor Participation Rate is hovering around 61% to 62% which is terrible. Even Biden has advised we are still down about 9 million jobs. However, if we obtain the 4% or more growth scenario, it would definitely cause inflation which will raise Treasury interest rates. However, the price increases due to inflation will negate any interest rate gains that occur. The only large economy that has grown 7% or more has been China. Growth in the stock market is entirely different. We could see 7% or more growth with measurement schemes such as the S&P 500. Remember, during 2020, the S&P 500 fell from January to about June when it rebounded back to its January level. Thereafter, it was up about 40 points to end the year up about 14%. That is not the sign of a growing economy. It is the sign of traders at work. Good Luck!
Of course more is 'better', but the 3 legged approach is where to begin.
Few of us should try and live 'debt free'. Better IMO to manage your debt well. Credit can be a path to greater wealth and independence down the road. Avoid debt on items that depreciate, like a daily driver car or truck, boat, RV etc. Use credit for investments that 'appreciate'. Accumulate available credit without using it, there may come a day where it will save your butt.