There are quite a few aspects of FPV, so a I’ll give a summary here. I’ll try to be concise so if any extra info is required or wanted, please let me know.
The first thing to look at when you’re flying FPV is the kind of aircraft, all the way up from a small Tiny Whoop to an X class (please not for beginners though!). In general, the larger props tend to give more flight time up to a point - it’s generally agreed that 7 inch props should be used for long-range because of this.
Another important thing to look at on your aircraft (excluding the advantages of different flight controllers etc, which I would love to talk about but would end up writing a massive wall of text) is the video transmitter, or VTX.
When looking at these, the first important thing is to check your local laws about what frequencies and transmitter powers you can use. Once you know that, keep in mind that more power tends to equal more range in open spaces, but can lead to more interference in places like abandoned buildings.
Another important fact to remember about the VTX is that you should manually select the channel on your VTX AND goggles as auto-scan sometimes picks the wrong channel and will cut out after a few feet. Also, never turn on your VTX without an antenna installed, or you risk damaging it. It is perfectly normal for your VTX to get warm on the bench when there is no airflow.
Finally, you will see people talking about Smart Audio - this is just a way to control the settings on the VTX from your transmitter.
Motors are very important. If possible, get brushless motors as they last longer and are more powerful.
When getting your first FPV quad, check out how repairable it is. It’s almost certain that at some point you will need to repair or modify it, so it’s good to know that before getting the quad.
Check what voltage your quad is designed to run at. If you have too little voltage, your quad will be underpowered, but if you have too great a voltage your quad may burst into flames (possibly a slight exaggeration to get a point across).
The ESC or Electronic Speed Controller is what tells your motor what to do, and you need one for each motor. If possible, get BLHeli_32 ESCs as they are more modern and natively support bidirectional Dshot so you can enable something called ‘RPM filtering).
When looking at flight controllers, the higher the value of X is in the naming format FX, the better. At the time of writing, F4 is the most common and F7 is becoming more popular. As I said, I won’t go into too much detail, but the higher the number, the more processes the CPU can complete per second so the more filtering and other leaguers you can have.
There are two main types of goggles - box goggles and slimline goggles.
In general, slimline goggles are more expensive, lighter, arguably more comfortable and tend to have a narrower field of view and better quality displays. Box goggles, on the other hand, have massive screens and tend to be cheaper, however they are larger and heavier so may be less comfortable.
If possible, get goggles with a diversity receiver (or if you get Fat Sharks of Orqas, get a diversity receiver module like Rapidfire). This has two receivers and can either merge the two signals into one (cleaner) signal, or just automatically pick whichever signal is the strongest.
The most commonly used protocol at the moment is FrSky's D16, with Crossfire becoming more and more popular not only for long-range, but just for general flying.
When picking your transmitter, look for Hall gimbals, which use the Hall Effect to measure movement instead of potentiometers, so last longer and (apparently- I haven t used them) feel nicer.
Much of your transmitter will be personal preference, about the ergonomics and whether you pinch, thumb or hybrid-pinch.
For anything more than 1S, you need a balance charger to make sure all the cells have the same voltage. To find the nominal voltage of a battery, multiply the number of cells by 3.7, as the nominal voltage of a single cell is 3.7.
I will leave you with this - don’t leave charging batteries unattended - LiPos are very dangerous if mistreated and can burst into flames if damaged or overcharged.