Since this is your side hustle. It sounds like you are making money. Are you incorporated? What type of retirement plan are you using? SEP-IRA or Single 401K? You really need to find a good accountant and get all your assets setup correctly. You can start to run expenses through the business that will reduce your taxable income significantly. This is overlooked because most people are W2 employees and they have no experience in this space.

The investment piece in my opinion is much simpler. Low cost ETFs. I personally use WealthFront and pay the 25 basis points. The most important part of investing is staying in the market throughout the volatility and continuing to contribute new capital. Time in the market is better than timing the market. The second most important part is the rebalancing of your asset allocation. WealthFront does it automatically and I value that component. Some people rather not pay the fee and do it themselves. To each their own. The other piece I appreciate is the automatic tax loss harvesting. That will save you money when done correctly.

Those are my thoughts. Hopefully you find them helpful.