What type of support is needed:

Recognise the nature of the decision.
context?
binary (yes / no)
fuzzy / uncertain
Irreversible
Optimal / satisfactory (see satisficing)

Recognise the importance of the decision.
potential risks / benefits
consequences

Recognise the role and responsibility of the decision-maker.

Recognise the factors which may influence the decision-making process:
decision style,
cognition,
management style,
personality,
and others ...

Recognise the information / data that is needed to support the decision.

Recognise the criteria to be used to choose the optimum (or best) outcome.