One of the thing about being interested in a lot of different fields is that you get to be a newbie over and over and over again. Also, you get to see a lot of them. Combine the two, and you quickly get the feeling that all newbies use a few of the same methods. Because I'm pedantic, I thought I would write them down and pose a theory connecting them.
1) Drowning in a Puddle
One of the most common mistakes is to radically underestimate the complexity of the field. In fact, I think that most of the other mistakes spring from this one. Similarly, the methods which don't result from underestimating complexity seem to be mostly methods to compensate for complexity.
Anyhow, newbies who suffer from this very common problem tend to have "the bestest ideas". (In case you have one of these bestest ideas, 99.99% of the time, it's crap. That includes 99.99% of my ideas. People aren't as smart as they think they are.)
Experienced people ignoring or deriding these ideas usually leads to...
2) Monolithic Conspiracies!
A rather astonishing number of newbies come to the conclusion that everyone in the field is acting in a conspiracy to squash newcomers and/or innovation. The louder newbie tends to hit a wall of silence broken only by occasional derision or condescension. Since everyone is acting the same, they must all be in on a conspiracy together!
Just in case some recognizes an accusation they have made, it is exceedingly rare for there to be such a conspiracy. I've never seen it. It's simply that they appreciate the complexity of their tasks, and you are at a level roughly equivalent to the bird that flies into a closed window.
I think this might be a major part of some people's paranoia complexes: if you act in a way which makes people want to avoid you, people will avoid you en masse. This can easily lead to thinking that everyone's in a conspiracy against you.
Anyway, they're not.
3) An Appealing Solution
A lot of newbies try to bypass the wall of silence with a direct appeal to the top of the food chain. These are the guys that email Bill Gates or Will Wright, pitching their newbie idea and desperately trying to get some funding or, at least, recognition.
This doesn't work, either. The big guys aren't going to invest in an almost certain failure. Everything that makes the other people ignore you is ten times more with them. They are, in fact, the worst people you could approach as a newbie.
Sure, you might get a word of encouragement. Some of those people are pretty nice people. But you won't get anything useful, unless all you're looking for is knowledge.
(Which is all I look for, these days. It really makes things easier. Most people are happy to talk to you about what they know. Or think they know, in some cases.)
4) Study study study study STUDY study study study
The last common tactic that I see is the "study" tactic. Once you realize that you're a total newbie, it is obvious that what you need to do is study so that you'll understand all the things these people understand. This is a tactic I tend to use.
But I don't think this tactic is any better than the others. (Except, well, the paranoid conspiracy theory tactic. I don't think there's much worse than that one...)
You see, theory doesn't actually accomplish anything. Your success in a field is largely who you have worked with. In some cases, "worked with" is simply "commented back and forth". It's people who know what you're capable of.
As you work with people, you'll learn all the things you would have learned by studying. Plus, you can still study. Win-win, right?
The thing is...
5) Nobody Likes Being a Newb
Everyone likes to think that they are among the best and the brightest. So everyone tries to minimize the time they spend with people treating them like a newb. You're the best, right? They shouldn't treat you like a kid!
Well, that's irrelevant. "Best" is also a scalar when your true potential is a vector.
It doesn't matter how brilliant you are, when you first enter even the simplest field, you won't know anything. If you sit there and make the newbie mistakes outlined above, you'll languish - at best, you'll slow down your progress. At worst, you'll alienate everyone and never make it in.
So, in my opinion, the best thing you can do to break into a field is to not take yourself so seriously. Don't go in thinking you're going to skyrocket to the top. Don't go in thinking you're better than the people in the field.
It's exceedingly rare for someone to have that level of talent. Even if they do, it still takes time and effort to bring yourself up to speed.
But even an untalented shmoe can integrate himself into a field by working diligently with others in the field. All you have to do is realize that you're probably mistaken. About everything.
Like me. I'm mistaken about everything. But (A) I admit it and (B) I'm less mistaken than most other people. :D