I am wrapping up grading my first set and, yes, time management is where most people go wrong (also not answering exactly what was asked).
My time management tip is to think of the exam in terms of points per minute. Out of 100 aggregate points each essay question is worth 7 (10 each but essay is weighted 70%) and each scoresheet 7.5. You have 180 minutes on the exam or 1.8 minutes per question. My suggestion then is to spend 12.6 minutes on each essay question and 13.5 minutes on each scoresheet. To simplify things you can just say 13 minutes per. You'll note that 13 per actually takes you to 182 minutes but you should be able to answer the first essay question very quickly making up those 2 minutes and leaving yourself a few minutes to double check at the end.
The temptation is to write forever if you get to a question you know a lot about, but there are no extra credit points and you will have a hard time scoring well if you have to skip a question or not write very much on it.
Wear a watch and when you start a question or score sheet write down the time 13 minutes in the future and stop writing and move on when you get to that time. Also within questions think about how you are spending your time. If you get the gypsum, finings, krausening question you will do much better with a brief few points on each than if you write a brilliant game changing essay on finings and ignore the other two parts. In this case I would recommend outline form and making all of the major points first leaving plenty of space between them and then go back and fill in the details. Paper is cheap and I would actually use a fresh sheet for each part of the question.
Practice questions under exam circumstances (maybe answer 5 questions in one hour) can help you with the mechanics of time management as well as getting a feel for what the pressure feels like and how fast you can write.
I know people will disagree with me on this but writing with a pen is much faster and much less fatiguing than pencil. I used a pen for the essay questions and a pencil for the scoresheets. If you write with a pen and make an error, just make a single clear strike-through and move on. Again, paper is cheap. Pen is also clearer to read when photocopied. For the pencil get heavier lead than normal so you can write a nice dark line even if this isn't your normal preference in pencils.