A test strategy is the set of big-picture ideas embodying the overarching direction or design of a test effort. It’s the significant values that will inspire, influence and ultimately drive your testing, and the overall decisions you have made about ways and means of delivering on those values.
Note that was “overall” decisions. A strategy is not a detailed plan. It’s the design behind the plan that you, as a skilled tester, have thought about and developed.
Fiona Charles, "Basics Revisited: Test Strategy" http://www.stickyminds.com/s.asp?F=S16783_COL_2