I don't have a complete list of them, no, but there are some obvious / widely used ones. Generally, we have to talk about quant and verbal separately.
Verbal is all about eliminating answers right from the beginning. The only way you know for sure that you're got the right answer is when you can also eliminate the four wrong ones. Usually, people find that they can eliminate at least one choice (and often 2 or 3) on verbal as they read through the choices. We can talk about how to do this, but this also requires a decent amount of knowledge of grammar and of how the different question types work - eg, how I make a guess on CR Draw a Conclusion is different from how I make a guess on CR Strengthen.
On quant, your initial goal is to try to get to the right answer, and that typically doesn't highlight wrong answers for you. If you want to find wrong answers, you actually have to switch tactics - that's not how verbal works.
On quant, you might:
- estimate, especially if (a) the answers are far apart, (b) you have some kind of chart, diagram, or picture that can help - eg, on geometry or on a rate/work question, or (c) there's a "split" in the answers, such as more than 0.5 or less than 0.5 on a probability question, more vs. less than half of a total distance or amount on a word problem, etc
- try the answers in the problem, especially if the answers are small whole numbers. If you do this, try either B or D first. For example, let's say you try B first. B doesn't work. You can tell you need a larger number, so you also cross off A (which is smaller). Next, you try D. D doesn't work. You can tell you need a smaller number, so C is the answer. If you try either B or D first, and then the other one second, and if you can tell whether you need a larger or smaller number each time, then you only need to try one or two choices before you find the answer.
- test certain categories of numbers on a theoretical problem: zero, one, negative one, integers greater than one, integers less than negative one, fractions between zero and one, fractions between zero and negative one. Use clues in the problem to help you decide which categories to test
- pick your own numbers on a variable-expressions-in-the-answers problem. If you do this, practice how to know which numbers will work best in the problem before you actually do it. (When studying) After you finish a problem, ask yourself whether some other number(s) would have been better, why, and if so, how you could have known to pick those numbers when you were just starting out. When you are evaluating the answers, remember that your goal is NOT to figure out what number represents each of those answers. Your goal is to figure out whether that answer might or does match the number you want. For example, if I'm looking for 10, I only care whether the number is 10. At any point that I can tell a choice will NOT be 10 (even if I don't know what the number will be), I stop and cross it off.
- look for "paired" answers on certain types of problems. This works on rates, work, sets, probably others I'm not thinking of right now. For example, Johnny and Susie are 20 miles apart and walking towards each other. Blah blah blah lots of other details. How far has Johnny walked when he and Susie meet? Answers are 6, 8, 9, 11, 12. Johnny and Susie are a "pair." Most common wrong answer on a "pair" problem: solving for the wrong person or thing. What are the pairs in the answers? By definition, you can only have 2 pairs (4 answers). Don't guess the "odd one out" - get rid of 6. (And, hey, we can estimate here too - half of the distance is 10. Can I tell whether Johnny did more or less than half of the work?)
- look for wrong calculations that lead to (wrong) answer choices. I once saw a combinatorics problem in which we had to pick 5 people out of a group of 9, along with various other constraints. One of the answers was 45. Even if you don't know how to get to the right answer, sometimes you know how NOT to get there.
- be wary of "leading" answers. If they ask for the maximum, usually the largest number isn't the right answer. Ditto the minimum and the smallest number. (Simply because there will be some people who choose the largest number
because it's the maximum. They don't want someone to get it right for that reason.)
And there are others. Note that everything I've talked about here requires you to study this in advance. You can't figure all of this out in the middle of the test. Plus, some of the strategies actually require practice so that you can use them efficiently and accurately.
Hey, here's an idea: someone start a thread for ideas on how to make educated guesses. People can submit their strategies, experts can weigh in, etc. Criteria: describe when and how a particular strategy could be used, ideally with an example (problem + explanation of educated guessing strategy for that problem).
