In addition to FPV I fly a DJI Phantom which uses smart batteries.
They give an accurate readout of their charge level, alerts when low, and you can set a time period (like 2-3 days) for when they will automatically discharge to a storage level so they are not stored full. They typically last 20-25 minutes.
Those are all nice features, however they are very big and expensive ($150 USD).
FPV freestyle and racing is usually under 5 minutes and batteries are not too expensive ($5 USD). Battery management is important but the impression I get from most is that pushing batteries a bit may shorten their lifespan but since the cost is not high it's a fair trade off.
I try to keep an eye on battery drain and when the "Low battery" warning comes on I start to land, but it's not the end of the world if I do an extra lap.
I'm sure others with a lot more experience can give you better advice. Good luck and let us know what you develop.