How can I achieve a grade average of 78% in my third year of uni?

It depends how your uni awards first class marks - if there are any marking schemes or examiners reports you can access this will help you work out what they want.
At my uni the important criteria for a first was originality in your answers, which was stuff like proposing new experiments, or original critique of studies (rather than just critiquing by citing other’s critiques or basic comments like small sample size without a discussion of how/why that is an issue). I did a few things to work towards a high first. I tried to not just read the suggested extra reading but search for more papers to answer questions the assigned reading left me with or pursue areas of interest it inspired, so in my essays and assignments I could discuss things other people might not talk about. I also made a point of learning in depth about how statistics for psychology works so I could critique results sections of papers better - this is actually a gold mine for criticism as psychology famously is having a replication crisis in part due to years of bad stats. I also tried to think about what you could do to answer unanswered questions in the area of interest and suggested new experiments that could fill those gaps or respond to the critiques about previous studies. Ultimately getting high grades for me was not just about knowing the content really well but forming my own evidence-based opinion on the state and outcomes of research in a particular area which allowed me to write strong essays.

As for révision for exams I went through all my lecture and reading notes and made flashcards for all the key facts and critical notes about each study I’d read. Later in my revision I made briefer flash cards to learn study dates and author names which just had author/date on one side and a brief cue as to which study it was on the other as by that point I’d memorised the content. My uni was weirdly big on citing names and dates in exams so I put a lot of time into learning that - you probably don’t need to if your uni is less focused on that! For open book exams I made notes sheets for each topic including key studies, critiques and past essay plans and put them in a big document so in the exam I could jump to the relevant notes sheets easily to get info for my essays. Making the notes also helps you know your way around the subject so you’re not wasting time looking things up to get ideas for an open book timed essay.

For assignments I tried to get them done with plenty of time before the deadline so I had time to read around the subject and come up with a line of discussion that could make the assignment really cohesive. It’s about having something specific to say in response to the question and choosing your sources and critiques carefully to say that, rather than just blurting out everything you know or think is relevant which can sometimes happen if you do assignments last minute!

I would note my degree was heavily research focused, we were mostly assigned journal articles to read rather than textbooks - I don’t know how you get taught at Leicester so some of this advice could be less relevant. That’s why the most important thing is to find out how your uni awards firsts and then plan your work accordingly. But hopefully some of the above ideas also help with this!

I attend the University of Leicester, studying a relatively easy course: psychology. To my peril, I did not put in the effort I needed in the first year, and more importantly, my second year of uni. I have an average of 56% for my second year of uni, and since my uni takes 33% percent of 2nd year's results and 66% of 3rd year results I will need an average of 78% for my third year if I want an average of a first on my final certificate, which I desperately need for the career path I've chosen. 78% is a high first and a seemingly impossible task.

I am planning a complete turnaround in life in general, but more specifically, the way I am handling uni. I am planning to do all the extra reading (of which I used to do only what is necessary for my essays and exams), but I feel like that is not enough. I will need the help of all you high achievers to tell me what has helped you achieve those higher grades in university. Also, I would like to know if this is even possible. The highest grade I've achieved for a module was 74%, so I want to know if there are people that have actually achieved that average (or higher) consistently. I am going to strive for it regardless, but I want to know if others have already been on this path, and if so, what it is that has helped you do that.

Leicester have an alternative method of classifying degrees, effectively upgrading near misses:

"A credit weighted average of at least 68.00% and modules to the value of at least 120 credits at 70.00% or better, of which at least 30 credits must be from level 6." https://le.ac.uk/policies/regulations/senate-regulations/senate-regulation-5/progression

That brings your target down to about 74 IF you get the 120 credits at 70+.

Thank you for fishing that bit of information out for me, I guess the load does not have to be as heavy as I thought it could be.

So, I checked and I have 90 credits at 70+, however that includes 1st year modules. Without them I only have 45 credits at 70+. Do you know what they mean by level 6?

Level 6 is third year. Yes, you ignore first year marks. So if you have 45 credits at 70+ from year 2 you only (!) need a further 75 in final year. And to average about 74 to pull your overall average up to 68+. Is that doable???

One other caveat is: "No more than 30 credits of modules from levels 5 and 6 with a mark of less than 40.00%."

We do 8 modules a year, each consisting of 15 credits. That means out of 8 I need to get 70+ in 5 of them. However my average needs to be 74 in total, so at least instead of having to get 78 average I can get 74.

It's doable but it's going to be extremely hard. I've gotten an 84 in first year, but that's first year. In second year the highest I've ever gotten was a 74 and now I have to make that my average for 3rd year... It looks grim but I'm really gonna apply myself and see how I do.

Also I have no modules from level 5 that are less than 40%, so that's a bit of good news.

Honestly, the best kind of help I can get right now is like that of @eeeli who at least showed me that there is a way forward. I'm still gonna try my hardest, but it's nice knowing that other people have achieved as high as I want to achieve, consistently.

Other than that thanks for the specification of a solution to my problem. I would have done the year with extra stress if it weren't for you

I attend the University of Leicester, studying a relatively easy course: psychology. To my peril, I did not put in the effort I needed in the first year, and more importantly, my second year of uni. I have an average of 56% for my second year of uni, and since my uni takes 33% percent of 2nd year's results and 66% of 3rd year results I will need an average of 78% for my third year if I want an average of a first on my final certificate, which I desperately need for the career path I've chosen. 78% is a high first and a seemingly impossible task.

I am planning a complete turnaround in life in general, but more specifically, the way I am handling uni. I am planning to do all the extra reading (of which I used to do only what is necessary for my essays and exams), but I feel like that is not enough. I will need the help of all you high achievers to tell me what has helped you achieve those higher grades in university. Also, I would like to know if this is even possible. The highest grade I've achieved for a module was 74%, so I want to know if there are people that have actually achieved that average (or higher) consistently. I am going to strive for it regardless, but I want to know if others have already been on this path, and if so, what it is that has helped you do that.

This is extremely helpful. Thank you very much. My uni also awards high firsts for originality, however almost all of our exams are open book (with the exception of one statistics exam which is a closed book MCQ)

You mentioned something which I thought is going to be helpful which is that there is a big problem in psychology of bad statistics and the replication crisis. I always knew this was a problem but I never thought about capitalising on it. Although I think I am fairly good at the mathematical side of psychology, I wouldn't say I am as adept or fluent in it as I could be. What helped you to become more confident in your statistical side of psychology? This question is particularly important to me as I would like to continue to do further study into psychology in the form of a masters/PhD. I am aware of the importance of being completely confident in statistics to pursue any kind of research and further education, or at least I would like to be confident in preparation.