I use credit & debit cards which yield "cash back" rewards, like 2-5%.

I use PayPal Credit and other credit card promotions to purchase more expensive, durable goods, and get 6-24 months interest-free financing.

Debt, when managed properly, can leverage additional wealth, but you also have to know your limits and be able to cover yourself in sudden downturns ... like owning IBM stock ... which I don't. I got burned on Enron a couple of decades ago and haven't gone back into the stock market since. Real estate is the real stuff.

Never buy cryptocurrency. Someone has already taken others to the cleaners.

Beware of giant funds like Blackrock. Pick your own individual stocks.