How do I answer a 'how far' essay question?

Example question: How far were economic pressures a decisive factor in persuading Saddam Hussein to invade Kuwait in 1990?

As this is an A-Level question, the candidate will have to assess the different opposing or mutually compounding reasons why Saddam Hussein decided to invade Kuwait in 1990. Knowledge of the historiography surrounding this topic - whilst useful - is not strictly relevant at this level so points, examples and evidence do not need to be tagged with scholars' names.

It's important for the candidate to plan before starting their answer by deconstructing the question and laying out the themes and corresponding structure their answer shall take. An emphasis should be put on the deconstruction of the question in order that the candidate ascertain what the examiner is looking for.

Deconstruction: this question is asking the candidate to measure the influence of economic pressure against other factors that may have influenced Saddam to invade Kuwait in 1990.

Now the candidate understands what is being asked, the candidate will recall that the other factors whose influence they will be measuring against the impact of economic pressures are: Iraq's relationship with Iran (in particular the Iran-Iraq War of 1980-1988), wider international events (e.g. the ending of the Cold War), the political changes in Iraq and Iran over the previous years, the impact of colonialism, Saddam's paranoia, the growth of Israel, Iraq's long-term dispute with Kuwait over Kuwaiti sovereignty, Ba'athist principles, and finally the 'green-light' theory. This and the deconstruction will form the candidate's introduction in the writing of their essay when combined with a line of argument.

The candidate will also recall the precise details of the economic pressures Saddam's Iraq faced in 1990 and how an invasion of Kuwait could alleviate these: more oil, compensation from Kuwait for protecting Arab interests in the Iran-Iraq War and revenge for driving down oil prices by producing over their OPEC quota. This information shall be utilised in the paragraph examining the titular theme.

The candidate will then cycle through the listed themes by comparing their probable influence on Saddam with each other and the titular theme. During this cycle they will need to constantly refer back to the question and state how newly stated evidence helps support their argument (or not).

The candidate will then come to a sensible conclusion on the basis of this comparison, restating their main points, what themes they have explored, and the limitations of their argument. This conclusion should finish with a final re-statement of their line of argument.