Document everything you do. Just as it is important for practicing doctors to document their clinical decision making, HMO physician administrators also need to keep good records and make sure their plans have clear pathways thoroughly documenting each step of the clinical decision-making process. Think about the legal consequences of what you're doing. Every time you deny some test or procedure, you must be ready to defend the decision. This isn't to say that you apply this analysis to every test or procedure, just the ones that you don't think are necessary.
Good medicine is cost-effective medicine.
The first rule of physicians is to do no harm. That means do no treatment or test that is unnecessary.