Action
From day one start building a view about how well the business systems support your business. Take advantage of the fact many people will tell you their pet peeves. These can help you identify where systems may not be working. As well as statistical performance data, complaints, faulty outcomes, time lags and other forms of process data will point to system weaknesses. Their absence may point to strengths.
Risks/Opportunities/Surprises
Beware of getting enthusiastic about big changes early, especially making accidental 'commitments' while being pleasant and building rapport with people in early conversations. While some types of changes can be implemented early on, leaders typically take time to learn about their situation before making too many major changes.
As you learn about systems, you may find some of your opportunities for quick wins.