What are the impostant factors that determine economic development?

Answer 1

Sustainability over a period of 15-30 years
Profitability
Impact on infrastructure
Positive Cultural Impact
Increase in country's self reliance (in house manufacturing)
Increased & Improved Public Goods (defense, health services, public safety, electricity, water)
Improved environmental conditions
Poverty reduction
Improved training & education

There are quite a number of ways to measure economic development. The important thing is to define what is important to that specific country and make it sustainable over at least 20 years.