A basic key to producing good essays is to start early and work steadily over an extended period. Build in time for distractions and problems (e.g. illness or disk failure), and allow for deadline bunching. Plan to complete well before the deadline to allow yourself some leeway. As a rough guide, you might allow three weeks for work on a course essay. The deadline is intended to help you with time management - make sure you adhere to it. Reflect on the feedback obtained on your previous essays. What strengths and weaknesses were identified? Think about how best to overcome the weaknesses.
For example, if your essays have been criticised for limited knowledge of the literature or lack of depth, this may indicate that you need to devote more preparation time and increase or change the breadth and depth of your reading; if criticised for poor structure or limited relevance, you are likely to benefit from spending more time on careful planning and editing/reorganising the final draft. Using course essays to work on your weaknesses can help you produce a better essay as well as help to improve your general writing skills.
Do some preliminary reading to help you choose an essay topic. The reading lists for the essays provide guidance on sources of preliminary reading. Generally it is useful to choose reading that is relatively recent, this is likely to include a summary of earlier work, some of which you may explore in more detail later. It can also be helpful at an early stage to make use of EconLit and the Library catalogue to check on the availability and nature of supplementary reading on a topic.
As should be obvious, you should try to choose a topic that you find interesting. This will help motivate you to work on the essay and is also likely to make the end product more interesting for the reader/marker. Note that interest tends to increase as you work on a topic, providing you don’t leave it all to the last minute....