When you’re taking the GRE, it’s easy to get caught up in a difficult question. ETS, maker of the GRE, knows this. That’s why questions aren’t presented in order of difficulty. Even if the test makers did want to put the questions in order of difficulty, everyone has a different set of strengths and weaknesses, so “difficulty” wouldn’t apply universally anyway.
All of this is to say, the questions that are most challenging for you will likely show up in random places in a section–so when you encounter one, skip it! Generally, you can tell by reading just the first line or two of a question (or analyzing the concepts involved), and make an informed decision about your likelihood of answering it correctly. The point is, the more quickly you skip over any question that even looks like it will be annoying, the better off you will be, since (1) this allows you a greater chance of answering all the questions you’re most likely to get right, and (2) you can return to any skipped questions during your remaining time, after you’ve knocked out the questions with which you felt most comfortable.
There is no reason to stick with a difficult question when you could be breezing through the more straightforward questions that happen to have been placed later in the section. Take a practice section or two to get used to skipping past initially-confusing questions, and you should notice not only a greater sense of comfort with the test, but a higher score as well!