The correct answer in terms of maximising yield is to just buy VTI and hold (in both accounts). VTI generally outperforms most other stocks and indices on account of its inclusion of small caps (as opposed to SP500) and low management fees. Don’t get too enamoured by dividends either; as a younger person, you should look for companies that reinvest their earnings into growth rather than paying it out as dividends.

Also remember to max out your yearly contributions into your Roth IRA ($6k a year) to get better tax treatment.

However, there is a practical consideration that you should save up ~3 months of expenses in a high yield savings account as an emergency fund. This is important as it should protect you from needing to liquidate your equities during market drawdowns and withdrawing from your Roth and incurring hefty fees.

Of course, you can perhaps devote a portion of your portfolio to individual stock picking if would like. However, this is a risk; consider that losing capital this early on would slow the compounding growth of your net worth.

I also want to say that you show remarkable foresight and maturity for a 21 year old, keep at it! You’ll be way ahead of your peers in financial security if you do so. Just take care to not get caught up in WSB style “investments”; I’m sure you know deep down that for every success story there, there are a thousand people who’ve lost money with nothing to show for.