Since our district will have a new chair soon, I'll throw in my two cents.
The Wood Badge advice is excellent. Have a Vision for the district. Second, using the old Wood Badge syllabus, Know and Use the Resources of the Group.
The two primary responsibilities for the district chair are:
Recruitment - Recruitment - Recruitment
Finance - FOS!!!!!!!
Communications!!!!!!!!!
Fill your Vice-Chairs with quality people. Find a good or great program person to be Vice-Chair for Program. That person will oversee Advancement, OA, Camping, Religious Awards, District Activities and the