ATTENTION FOR THE 15 MARKER!!! As an f581 retaker this year I have done this exam before and I had all the knowledge and some technique as shown in the "a" that I got in f582, however you must be aware that you can easily slip up as I did, getting a "d" in f581.
You've probably heard this before loads but read the full question and make sure you answer it. Every paragraph should link back to answering the question despite how trivial it may sound, the exception is for defining terms at the start of the question. For example if the question asks something along the lines of "Discuss to what extent indirect taxation is effective in correcting negative consumption externalities arising from market failure" make your point such as indirect taxation increases the cost of production which shifts supply to the left, leading to reduced supply which increases the price. This in turn reduces consumption and therefore reduces the negative consumption externalities and thus correcting them to some extent...
Some tips I would give aside from this is to separate your for points to your against points and also "It depends on..." is not a counter point and should be done at the end as analysis. This is my personal preference although you don't have to do this.
Finally, if the question refers to the extract that you are given and says to use it...USE IT. This is both easier and will actually get you the marks. p.s. I know how annoying it may be to turn all the way back to the extract but it's worth it. I wish they gave that separately but hey, what can you do?
Hope this helps, Mushto