Uber and Lyft work in Miami, Lyft was recently giving great incentives to use their service.

Here is an uber invite code 2dfqt if you'd like
Here is a lyft invite code anthony125622
Should get you at least a free ride on each service.

I use Uber almost everywhere I go including international travel, from Peru, China, Australia, Panama. I've never had any problem.

It is typical to not tip.