Get a credit card at 18 and pay it off monthly. Buy a home with an FHA loan (3-4% down). Open a Roth IRA at Vanguard and contribute a few hundred dollars monthly starting in your early 20s. Decades of compounding can grow that into a tax-free million by retirement.
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Do you want to be a millionaire and much more by the time you retire? If you're a young adult or you know a young adult, write these things down. The first thing you need to do is get a credit card. You can get them as early as 18. Get anyone that you can qualify for and pay it off every month. Secondly, as early as you can swing it, buy a home with an FHA loan. The credit score you need to qualify is very low and you don't need much money down, 3 to 4%. Next, and this is huge, start yourself a Roth IRA. Vanguard is a good place to start something like that. The earlier you start, the better. If you're in your early 20s, just a few hundred dollars a month means you will be a millionaire by the time you retire, and it will all be tax-free.