What should be the strategy which a key account manager supposed to focus?

i did not use a unique strategy on managing KA, depending from many/different thoughts, adapting local/global approaches but overall I have evolved my strategy from a "purely opportunistic" sales approach to major accounts, into a "strategic company decision" covering both corporate/accounts and operational/financial aspects.

This is a sequence I use in order to excel in managing KA:

1-Strategy (Create a key account strategy driven by corporate strategy and build a competitive growth that defines growth sources and key account added value)

2-Organization (Install cross-functional teams with a multi-disciplinary approach according to SM and define the role of marketing and sales)

3-Measurement (Measure success and progress, define/set/monitor/analyze value-adding KPIs and strive for a full costing measurement)

4-People /Team (Define roles/responsibilities, foster knowledge and create brand awareness, appoint high-level key account profiles)

5-Processes & Tools (Install a simple/clear/effective/modular key account network on regular performance reporting)

Finally, as my humble opinion, the  role of Sales and Marketing needs to be calibrated according to the corporate KA strategy. Sales and Marketing need to go hand-in-hand and work collaboratively toward the common goal of profitably increasing revenue and customer excellence through shared processes, resources and metrics. It will take great courage by senior managers to abolish the historically installed turfs such as Sales’ “ownership of accounts” and Marketing’s “ownership of product and communication”. This win-win strategy will lead to a  common ownership of results.