It is really frustrating when your teacher keeps telling your that your economics essay is lacking "rigor" or "depth" or "content" but fails to offer any practical solution besides telling you to study harder. We can't really blame them, because doing the hard yards is part of the requirement if you want to ace A level economics. That means you really have to spend time hitting the books and trying to memorize stuff. However without a good strategy, this is likely to the academic equivalent of shoveling water out of a sinking boat, except in this instance, more information is leaking out of your brain than you can keep them in. How then should we maximize the effectiveness of our studying?
1. Don't get "lost" in the lecture notes
It is very comforting to just spend hours reading lecture notes and praying/hoping that your grades will jump. Every time I say this to my student, they smile, because they know that it is true! Maybe you are also finding comfort in the bosom of your lecture notes. Reading lecture notes are important, but you need to be very aware of what exactly the lectures notes are for. Lectures notes are largely to provide you with explanations that you have to replicate when explaining economic theories. In other words, it kinda serves as a "wikipedia" of sorts, to teach you and show you how theories should be explained. The issue is that if you are merely reading lecture notes in a chronological fashion, by the time you get to page 40, you are going to forget what was on page 2. It is neigh impossible then, to remember what you studied in the previous set of lecture notes when you moved on to another chapter. What you need here is to "scaffold" your knowledge. Don't get lost in your lecture notes. Don't read it like a story book. Build a "scaffold" by first asking yourself: what are the key segments in the lecture notes? How many key theories did you learn? How many sub-theories do each of those key theories have? By giving some sort of the hierarchy and logic to the information, it becomes infinitely easier to recall the concepts that you have learnt and apply them to answering questions. This brings me to the next point.
2. Active Recall, Active Recall, Active Recall
Active recall is forcing yourself to remember something. The simplest form is to read a page of notes, and then trying to type it out again. If you fail to engage in any sort of active recall process during your revision, you are essentially gambling that somehow you can retain the information and reproduce it during the exam. I am sure you know by now that this approach will end in tears, no matter how hard you pray that it works. With all the gadgets and technology available to us today, there is really no excuse to not practice active recall. The simplest thing that you can possibly do, is to read your lecture notes, then voice record yourself explaining the concept you just read. Just read about public goods from market failure? Close the book and recite the theory to yourself, and record it. It doesn't have to be word for word, but if you don't even think you make sense, there is no way the examiner will understand what you are trying to say. Beyond trying to remember explanations for key economic theories, it is also important to be able to list down the key concepts that you need to know. No details! Just key concepts first! If you don't know what you need to know, there is no way you can remember the explanation for them. Which brings us to the final tip.
3. Bird's-eye View
In content heavy subjects (not just Economics), it is important to have a "bird's-eye view" of what is in the subject. It is neigh impossible to memorize the notes cover to cover (unless you have an eidetic memory of course), and so some structure is needed to memorize the concept. This is what mindmaps are supposed to achieve. I am convinced that many of you do not believe in mindmaps because you are simply using them wrong. A mindmap is literally what the name suggests: a "mind map", a "mental map" of what the content is about. So if you scaffold your content by going down the layers, it makes it infinitely easier to recall the key concepts and utilize them in your answers. For example, market failure can be broken down into four major pillars: efficiency of the free market, sources of market failure, efficiency of government intervention and government failure. There are 7 sources of market failure: merit/demerit goods, public goods, externalities, market dominance, asymmetric information, factor immobility and inequity in income distribution. By layering your knowledge and first knowing what you need to know, you will be better equipped to dissect questions and identify the topic area that you are being tested on. If you do not even remember that merit goods is a thing, there is no way you can remember that you need to know about the underlying reasons for why merit goods are underconsumed. Thus when faced with questions, you will be relegated to "flinging" whatever knowledge you can think of, rather than purposefully crafting an answer that unpacks the key concepts related to merit goods.
Conclusion
Sometimes it is really hard to see beyond the U grade or the S grade that you are currently getting, especially if you put in a lot of hours into revising for Economics. However, the hard truth is that if you don't revise intelligently or purposefully, those hours spent on reading notes or even making notes aren't going to pay off and you will still fail. If you apply these techniques, you will greatly improve your chances of retaining the key concepts needed to answer questions, and reduce your need to "guess" and "gamble" that you will be able to produce the relevant concepts and write a good quality explanation.