Learn to say "No"
At times, making a trade-off requires nothing more than specifying what you won't do—and not bothering with articulating what you will do. Setting boundaries as such is tremendously valuable because it enables you to not waste time on projects or initiatives that you don't support or that will be shut down later.
For example, suppose your group is evaluating the possibility of creating tiered versions of a product—high-end, mid-market, low-end. You've made a strong argument against introducing a low-end product: "It'll hurt our brand image, and it will generate lower profits for us." In this case, you might indicate your trade-off decision by saying something like, "I don't know what a high-end version of the product would look like. But I do know that we won't do a low-end version."
By defining the trade-off in this way, you help your group to focus on the acceptable courses of action—and to develop or maintain strategies for ensuring success.