The Dunning–Kruger effect and you
According to Wikipedia,
The Dunning–Kruger effect is a cognitive bias in which unskilled people make poor decisions and reach erroneous conclusions, but their incompetence denies them the metacognitive ability to realize their mistakes.
The more ignorant you are about a subject, the easier it seems to you. When I was starting out as a translator, I got bitten by this more times than I like to remember.
Paper and pulp? Why not — how hard could it be? I use paper every day, and once I took a paper-making class. A survey on healthcare in Vietnam? I just had my checkup last month, and I LOVE Vietnamese food. And so on.
Even when I glanced over a document ahead of time, it seemed easy — it wasn't until I actually dug into the translation (after accepting the job, of course ) that I realized I was over my head.
As a corollary, the more we know about a subject, the more likely we are to know our limitations. For example, although I specialize in IT and telecoms, I refuse to do electronics or chip-making stuff. I know how hard that stuff is.
The problem with the Dunning–Kruger effect is that you actually believe that you can do a good job. How do you know to turn down a job when you think you can do it?
After a while, I developed a kind of sanity check when offered a job in a new field. I ask myself how long actual experts in the field study. Then I ask myself if I have studied that field long enough to duplicate their understanding.
And then for good measure, I think about all the botched translations I've seen in my fields by people who said, "Why not — I own a copy of Windows and play Minefield ALL THE TIME."