What factors are the most important to be considered when attempting to influence consumer behavior during the development of marketing strategy?

tough question! Influencing behavior but which one? If you know your product or service then you can tell why people are using it and more importantly what need(s) the product fulfill. Behavior encompasses social, psychological, economic patterns you can recognize amongst a group as large as a community and beyond. To influence behavior, you need to recognize the hot spot and adapt your message to hit that spot. There is no unique factor in my opinion, but look at the impact caused by using the product, just like in reverse engineering, to give tangible elements that will model the behavior because people tend to keep out from things that they perceive as not good for them. That is maybe the best way to entice them or lead them to your solution.

Psychological ,Social, Cultural &Economic Factors.