There's no simple method of determining score from % correct. As you acknowledged, your score depends greatly upon the difficulty of the individual questions that you got right and wrong. Sequence matters, too, although missing more at the beginning is not necessarily the problem people think it is. Missing many problems in a row usually means that you will dip down into lower-level questions and reduce your score.
It's also important to note that the quant and verbal sections don't really work the same way. Most people who are scoring well in quant will get about 60% correct, regardless of score. (This changes at the extremes, but not always by very much.) However, in verbal, you need to get more like 70+% correct at a fairly high difficulty to score well.
In the end, the best thing to do is to avoid running afoul of the scoring system--don't time out, don't overinvest on individual questions, and avoid long stretches of missed questions--but otherwise to think about the algorithm as little as possible. It isn't simple or transparent, so all you can do is try to maximize your overall performance and keep improving. Good luck!