I'm pretty sure this isn't a dot-point on the syllabus, however I'm assuming you're doing it for a SWOT analysis? Or you're talking about Factors Influencing Consumer Choice.
Anyway, the external factors that will impact include:
- Economic Factors (including the state of the economy, whether we're in a boom or a recession) - this will impact the strategies as businesses will have to target different aspects in order to entice in different times (e.g. in a recession, they'd emphasise on strategies such as price penetration)
- Government Factors (including legislation) - this will again vary the buying patterns of a consumer, hence the business will have to focus on different strategies.
- Social cultural (factors including: culture, socio-economic, family and reference groups)
- Psychological (factors including: perception, attitude, lifestyle).
Hope this helps. =)