The tip amount is totally optional, and the driver will appreciate whatever you give them.
Don't be afraid of Uber. It's really easy. The big key is to be standing at the curb where you will be picked up before you order the ride. Don't order while in baggage claim, because you will probably get hit with a cancellation fee when the driver arrives before you do. Because of airport security regulations, drivers are not permitted to sit and wait for passengers -- you are there, or you're not.
You will receive a description of the car, the tag number (Florida has only rear tags, so that's not too helpful), and a picture of the driver. You will also be able to see the car approaching you on your rider app, and you will have the ability to call or text the driver if you need to give them any information about where you are. (All calls/txts go through intermediary numbers, so you will not have the driver's real phone number and they won't have yours. After the ride is completed, neither of you will be able to contact each other.)
If you can pick a location a little away from other people waiting, that will make you easier to see and easier for the driver to get to.
Relax...it's easy!