Most people will suggest stocks, or real estate. Some may also suggest cryptos. My philosophy is to do it all, and diversify.
While you may want to "hodl" your crypto, and hope it goes up, imo, you're better off staking the crypto, as mentioned in a prior blog post. Of course, if you don't have a lot, then staking and getting rewards may not work as well as you hoped, which is where you may want to join a staking or inflation pool. Hodling, day trading, and scalping can be options.
This takes a look at stocks vs real estate.
But what if you don't have the time, or knowhow, to flip homes, or want to bother with with tenants? You could put your money into a REIT (Real Estate Investment Trust). You could buy a turn key, where a company handles all the specifics, and pays you from the profits. You could invest in notes (you buy a mortgages, and collect on it). You could also become a private lender, or look into working with a hard money lender.
Of course, with stocks vs real estate, you can almost certainly buy and sell when you want, without waiting for days for someone to buy the house (which is why I've never gone for flipping). Fees for transactions are lower with stocks, than trying to buy and sell a home. Also, property taxes can eat at profits.
Like always, research, consult with professionals, and see what works.