How should put in my essays for 25 mark questions?

When considering what is needed of any a level essay question, the best place to start is the mark scheme for past papers.

These mark schemes give a consise explanation of what is needed to acheive top marks. 

The mark scheme breaks the marking down into four sections, 'knowledge and understanding', 'application', 'Analysis' and 'evaluation'. 

Knowledge and understanding is simply demostrating that you are aware of economic concepts and reasoning relevent to the topic, such as the main economic indicators and main agents of an economy. This is of course the foundation of the essay.

Next we consider application. Application marks are rewarded when the writer correctly applies theories and concepts to their essay, without discussing points that aren't relevent to the issue. This is when marks are rewarded for using real life data, such as government targets, the current state of the economy and current issues. Examples of real life will be frequently discussed in tutor sessions, to help demostrate complex theory, and it's advisable that the student keeps record of examples to use in essays later. 

Analysis marks are rewarded when the writer correctly explains how the issue being discussed effects the economy in different ways, and how the agents react. The markers look for a consise and relevent logical chain of reasoning. This part of writing comes with practice and it's advisable that students do lots of past papers to try make their chains of reasoning clear and consise. This part of the essay usually contains some course of action that could be taken to improve the current state of the economy with regard to this issue at hand. The writer should give a few different areas to consider, all with a unique chain of reasoning.

Marks are rewarded for evaluation when the student, using his knowledge, gives an overall explaination of the implications and points the writer made in his analysis. The writer must at this point assess how prominent the issue is, whether it is worth fixing, how important it is compared to other issues, what knock on effects will occur from making changes and how difficult it will be to change it.  

It's advisable that the writer evaluates throughout their essay, to avoid running out of time near the end, but if time is left over, giving an over all evaluation of what arguement they think is best and why is a good way to finish the essay.