How should I pace myself on the GRE?

The core principle is to spend your time where it buys the most correct answers. That means doing the questions you're confident in first, then working through the ones you think are solvable but aren't sure about, and leaving the rest as quick guesses.

Use the mark-and-review feature to manage this. Within the first 30 seconds of each question, make a quick call: is this one you're confident you can solve accurately and efficiently? If so, do it now. If you're on the fence, mark it and move on to come back after you've collected the easier points. If it looks like one of the hardest problems in the section, log a guess and don't plan to come back.

You should always plan to leave at least one question as a permanent guess, never spending a minute on it. That's not giving up. It's buying yourself time to be less rushed and less likely to make careless errors on the questions you're more likely to get right.