Best Way to Get Around Miami Without Spending a Fortune?

Hey everyone,
I’m heading to Miami in the next couple of weeks and was wondering what the best (and most affordable) way to get around the city is. I’ll mainly be going to the beach and catching a soccer game or two, so I don’t need full-time transportation—just something practical to avoid racking up a huge Uber/Lyft bill.

I’m 20 years old, so renting a car is pretty tough (and expensive with the underage fees).

Side note: If anyone in the area has a reliable beater they’d be open to renting out to a friendly Canadian for 2–3 days, I’d be happy to negotiate a fair price and draw up basic contract terms. Totally serious—just trying to get around without breaking the bank.

Appreciate any advice or offers—thanks in advance!