When it comes time to choose your radio frequency, luckily, for new pilots, there are only a few options from which to choose. Amongst each of those decisions, the choices are very clear cut, so it makes it a lot easier to know what the right choice is. The options, in terms of frequency, are 2.4GHz, 433MHz, and 900MHz.
2.4 is the most common of the radio frequencies. Standard radios like Taranis, Futaba, Spektrum, Graupner, etc all run, by default on the 2.4 frequency. Coincidentally, this frequency also happens to be the same frequency that your average WiFi network run on, so it usually also tends to be the “dirtiest,” with the most opportunity for interference. That being said, we rarely see interference on the 2.4 frequency (at least in terms of RC connection), because there are very powerful channel switching technologies built in to radios and receivers these days. 2.4 GHz transmitters generally have a fairly low transmission power and low gain antennas due to FCC and HAM license restrictions, but those signals can be boosted to higher transmission power and equipped with higher dbi antennas. (boosting your radio power above the standard will likely take you out of safe requirements for not having a HAM radio operator’s license). Pilots have reported nearly 20 mile range on 2.4 with the proper antenna and power setup. However, since most of us don’t boost our power, the average long distance that we can achieve is around a half mile.
The other major type of control system is LRS or “long range system.” These are products aimed at those that want to securely fly out at longer and longer ranges than standard short-range transmitter/receivers would allow. The range on these systems is extremely high. Reports of 100km round trip flights are regularly reported, with video reception being the limiting factor on distance, rather than RC connection. Both 433 and 915 are very similar. Depending on your country/region, one or the other will have more or less interference, and you want to make sure that flying that band won’t interfere with public communications systems, which would land you with hefty legal charges. LRS Systems generally have large antennas and the equipment is still relatively large, so it can be tricky to fit these in smaller crafts, though some recent technology is starting to bring the size of that radio gear down. However, LRS systems are still generally reserved for larger rigs or fixed wing planes that can better benefit from the extra range capability.
In general, if you’re mostly going to be doing short-range/park flying, 2.4 GHz control, which is the cheapest and most common, will be perfectly adequate. However, if you decide later in your FPV career to start attempting some longer-range missions, it’s simple enough to upgrade your existing gear to LRS systems like 433 and 915.