18 year old making $60k a year; how should I invest? Traditional or Roth IRA?
In asnwer to your questions: As @joetaxpayer said, you really should look into a Solo 401(k). In 2017, this allows you to contribute up to $18k/year and your employer (the LLC) to contribute more, up to $54k/year total (subject to IRS rules). 401(k) usually have ROTH and traditional sides, just like IRA. I believe the employer-contributed funds also see less tax burden for both you and your LLC that if that same money had become salary (payroll taxes, etc.). You might start at irs.gov/retirement-plans/one-participant-401k-plans and go from there. ROTH vs. pre-tax: You can mix and match within years and between years. Figure out what income you want to have when you retire. Any year you expect to pay lower taxes (low income, kids, deductions, etc.), make ROTH contributions. Any year you expect high taxes (bonus, high wage, taxable capital gains, etc.), make pre-tax payments. I have had a uniformly bad experience with target date funds across multiple 401(k) plans from multiple plan adminstrators. They just don't perform well (a common problem with almost any actively managed fund). You probably don't want to deal with individual stocks in your retirement accounts, so rather pick passively managed index funds that track various markets segments you care about and just sit on them. For example, your high-risk money might be in fast-growing but volatile industries (e.g. tech, aerospace, medical), your medium-risk money might go in "total market" or S&P 500 index funds, and your low-risk money might go in treasury notes and bonds. The breakdown is up to you, but as an 18 year old you have a ~50 year horizon and so can afford to wait out anything short of another Great Depression (and maybe even that). So you'd want generally you want more or your money in the high-risk high-return  category, rebalancing to lower risk investments as you age. Diversifying into real estate, foreign investments, etc. might also make sense but I'm no expert on those.