If you're in secondary school and worrying about exams, this is the post for you.
I was in 6th Year last year and remember being bombarded by ads for paid services - grinds, workshops, revision books, ebooks with tips for "easy A1s", website subscriptions. They annoyed the hell out of me so I didn't use them (or do almost any of the work my English teacher assigned) and still came out with an A1. Here's how.
Disclaimer: Everyone's brain works differently. I have a knack for languages (and maths...). If you are doing grinds or using some other paid service already and they're working for you, cool. This is how I got the A1 (accidentally).
English is an interesting subject, in that you're not so much being assessed on your knowledge of the syllabus as on you and your ability to express yourself. In Physics, all that matters in the exam is that you can do the questions; in English, it's a lot easier to do well if you have interesting things to say.
I got the A1 pretty much accidentally, without doing almost any English homework or paying anyone or memorizing notes. In my opinion, the best way to do well in English is not to spend a lot of time focusing on doing the English exam, and just try improving yourself and your written expression overall.
Without further ado...
Read. The most obvious but most important one. I spent my whole childhood reading (one of my more nerdy successful challenges was to read 30 books in June 2012) and that's the easiest way to do well in English, but just get into the habit of reading as early as you can. I didn't read a lot of books in 5th or 6th Year because I didn't make time for them, but I did read plenty of longform articles from sites like the New York Times, the Washington Post, The Atlantic, Politico ... and scientific journal articles in my areas of research, antibiotic resistance and nanotechnology. Reading teaches you vocab, fixes your grammar, gives you interesting things to say -- and it's fun. If you don't like classics, don't read the classics. Read something you're interested in - there's probably a journal about whatever you're interested in somewhere.
Write (longform). Write something you're interested in. I always found the writing assignments given to us in class boring so I didn't do them (I especially didn't like handwriting things so I typed). However, I wrote tons outside class. I became a professional writer in June 2014 and have been paid to write freelance articles on all sorts of topics (from entrepreneurship in the Caribbean to mortgage insurance to hospital addiction to the meaning of life) since then. I wrote two blogs. I wrote letters to my friends. I wrote tons. So: write. But if you don't want to write the kind of things your teacher tells you to, unless there's a specific reason (like you need practice with speeches), don't. Write something you're interested in and you'll have a much better time. It's so important to practise getting your thoughts out quickly, coherently and elegantly.
Memorize quotes (nothing else) by writing them out in the days before the exam. An exhaustive list of what I memorized for the English LC exam: 10-12 quotes for each of 5 poets, about 6 King Lear quotes, about 6 Comparative quotes. So if someone says that the Leaving Cert is just about rote memorization, bear in mind that it really depends on how much you choose to memorize. Out of my 7 subjects, History was the only one in which memorization made up a significant amount of the marks.
Please don't memorize points or paragraphs and especially not essays. I cannot emphasize this enough. Don't do it. First of all, it's cheating if you're memorizing some sample essay, secondly it's risky if you blank, thirdly examiners are probably sick of it. You're not supposed to be being assessed on your memorization ability, so don't make the exam about that. If you have difficulty with English, get checked for dyslexia, don't memorize things.
Show your personality. One of the biggest reasons I did well in English has nothing to do with my English -- it's to do with my scientific research. I've spent the last few years carrying out research projects in specialized areas, so I showed off that knowledge in the exam, like when I told Obama he should be spending less on NASA given the dismal state of healthcare, with glioblastoma's terrible prognosis and antibiotic resistance's spread. Whatever you're into, put it on the paper -- the examiners are bound to be so bored of reading the same thing over and over.
Study five poets. Why increase your stress any more than you have to? I studied (and by that I mean read their poems, made up my own mind about what they were saying instead of learning off notes/analysis from the book and learned some quotes) Yeats, Plath, Durcan, Bishop and Dickinson; the latter three came up and I picked Durcan. If I'd only studied Yeats and Plath (my favourite two), I would've been screwed, like a lot of people who banked on Yeats. Just don't add to your stress on the day. Learning an extra few quotes is worth it.
Write concisely. Ignore people who tell you you must write 7 pages for your Comparative, or 5 pages for your essay. Write enough to express your point. Nobody wants to read 7 pages of waffle. I wrote 4 pages for my Comparative and 3 pages for my essay and for my Question B. It's better to overwrite than underwrite, but still; use as few words as you can to say something interesting.
I don't know your school, so I can't tell you categorically not to do your homework. It's often very helpful to practise writing essays/articles/speeches/blog posts. I just think it's better to do work on stuff you're actually interested in, because you'll do it better and be more authentic on the exam paper. So, basically: don't make this into a rote learning exercise by learning notes, write concisely, don't add to your stress by gambling on the paper, and work to improve your overall English skills instead of just training for the exam.