Lesson 1) Start simple.
I initially did a ton of research and bought every component I thought I wanted. (OSD, Autopilot, TX, RX, goggles, diversity, antenna tracking, head-tracking, etc.). I spent countless hours trying to get it all working together before I even attempted my first flight. I figured my technical prowess made me somehow immune to the KISS rule and I'd be fine diving in head first. All I accomplished was making myself frustrated.
Eventually, I stripped the system down to the bare minimum (Camera, transmitter, receiver, and LCD screen) and just FLEW (with a spotter, of course). It was AWESOME! I landed the plane, took it home, and added the pan-tilt system, then flew again. Then I added the goggles, and flew again. I learned that each component made the experience completely new again, and even more complex. The downside? It takes a LOT of time. Like most of you, I have a day-job and a family, which means LIMITED time to work on this stuff.
Besides, had I managed to get myself flying with all the gizmos on day-1, I likely would have crashed due to "too many moving parts
". Despite having a nearly unlimited budget, and lots of technical prowess in both electronics and radios, I was eventually forced to walk before I could run.
Accept the fact that it's going to take you a few weeks (or months) to get all the toys working, and focus on the small victories.
Lesson 2) The little things matter. A LOT.
I really thought the "little things" were for people trying to squeeze an extra half-mile out of their setup, or trying to make the picture just a little more clear. I was dead wrong. It turns out, the little things are the difference between amazing success and complete failure. When someone tells you that you ought to install a filter somewhere, or shield your wires, or move your GPS a little further from your transmitter, DO IT. I learned that these (seemingly) little things can have more of an impact then spending hundreds of dollars on newer / better gear. And in some cases, they're the ONLY solution.
Lesson 3) A lot of this gear doesn't work with each other.
Do a LOT of homework before you buy stuff to make sure it's all going to be compatible. (Example, I bought a pair of FoxTech goggles, only to learn that the built-in receiver wouldn't work with my ImmersionRC transmitter!). A little research before my purchase would have saved me a lot of headaches here. It simply did not occur to me that a 5.8ghz receiver might not be compatible with another 5.8ghz transmitter. Another example? None of the head-tracking systems will work with my JR-9503. Choose your gear carefully.
Lesson 4) When deciding whether you should be using 5.8ghz, 2.4ghz, 1.2ghz, or 900mhz -- the answer REALLY IS "it depends".
I just couldn't come to grips with the idea that there would be such dramatic difference between these. Here's the rub: There are pros and cons to each (you should do enough research to know EXACTLY what those pros and cons are). But in the end, it really depends on where you happen to be standing. A half-mile in any given direction might completely change your choice. So how do you pick? The truth it, you're probably going to end up trying them all.
Lesson 5) We all dream of flying 15+ miles and zooming around the countryside, but it's not realistic until you've got years of experience.
I know, I thought I was immune to this rule too. I figured if I spent enough money and bought top of the line everything, and all the different gear I needed, I'd have my plane flying 10+ miles within a week or two. "Surely", I thought, "the only reason MOST people aren't flying those distances is because of budget, or lack of RF knowledge". I got humbled REALLY quick. My first flight where I flew beyond the range of my spotter was an immense victory (it was probably my 10th flight). I'm still aiming for the 2-mile mark. Set your goals small, and know that big goals mean big-time experience.
Lesson 6) This stuff is actually not that complex, but if you're not comfortable holding a soldering iron, it's probably not for you.
Lots of wire cutting, splicing, soldering, and other such fun. At first, I wanted to avoid all that and try to get something that would "just work". After dozens of hours and countless dollars trying to do just that, I picked up a soldering iron a fit of frustration one day and realized it's MUCH easier to just build the things you need than it is to try and find / order everything.
Lesson 7) A little understanding of RF theory goes a long way.
Thank heavens I came into this with tons of ham radio experience, so I understood simple concepts like why you don't want to run a transmitter without an antenna, why the orientation of the antenna matters so much, or why 500mw on 5.8ghz is less effective than 200mw on 900mhz. Get your ham radio license and really understand what's in the test rather than just memorizing the Q&A.
Lesson 8) The gear works, but it's not commercial grade by any standard.
I was surprised to find that most of this stuff comes straight from China, it's poorly (if ever) documented, and it's really up to you to figure out how to make it all work together. While not the end of the world, it certainly was not what I was expecting to be getting myself into. The fact that the gear is not particularly robust makes it all the more important to spend the time to get it EXACTLY right, and test it, test it, and test it some more.
Lesson 9) To whatever extent possible, try to be alone.
I'm not saying you should fly without a spotter (you should have a spotter, especially when you're new). But I learned quickly that if I was with a group, there was a lot of pressure to perform. I learned that my time in the field was best spent when I could spend as much time as I needed on a particular problem, without feeling the pressure of having other folks watching or waiting. Find a wide open space where you can tweak, fly, repeat as much as you need.
Lesson 10) The guys in the online forums are actually super nice and helpful as long as you approach them with the appropriate level of humility.
I've been extremely impressed with the community here. Ask your question nicely, provide the relevant detail, and explain clearly the results you are trying to achieve. Then, re-read your post to make sure the problem is well presented before you submit. Be prepared to do a lot of reading (sometimes answers to questions come in the form of long threads). Be understanding if nobody wants to repeat what's already been discussed.