For whatever reason, people are more far more amenable to adopting ethical frameworks than moral ones, and a dearth of ethics can prevent your team from obtaining the goals it has in sight. To work ethically, though, you and your team members must agree on what that means. You have to determine what set of ethics you must apply.
Need for Standards
It's worthwhile to develop a set of ethical guidelines. Whether you generate them or there is some pre-existing set of rules in your organization or field doesn't matter. But if you have guidelines, then you can properly set expectations among the team members. There are a number of sources you can mine for suggestions:
Interview those in your field
Check if your organization has ethics guidelines
Poll members of your team
Ask appropriate academics
Look at books on the subject
There are two approaches you can take. One is to develop an exhaustive list of rules that cover virtually any possible circumstance. But that sounds so … exhausting. Instead, use an approach similar to the one the European Union uses to handle many regulatory issues. Come up with governing principles and allow team members to use their judgment in making their actions compliant.
If you want people to be ethically compliant, you must make them aware of this. Many organizations go about this the wrong way. They include a note about ethics in an employee or volunteer handbook. In some speeches, executives might note how they greatly value ethical behavior. This is nothing more than window dressing, a hope to answer potential legal actions in the future — and it is completely inadequate.
Ethics are not morality, and sometimes the ethics that cover a given occupation or endeavor are not necessarily obvious. For example, why should it have been unethical at one point for lawyers to advertise? Clearly, they were going to find other ways to market because they needed to bring in business. If you were entering the legal profession at that time, someone would have had to tell you outright that advertising was forbidden.
You need to train your team in ethical behavior, just as you would need to train people in basic operational matters such as how to use intra-office mail. Schedule people in groups, go over the requirements, and create a discussion. Try some role-playing to help team members understand the potential pressures they'll face and the range of options they might perceive. The more people engage with the concepts, the deeper their understanding will run, and the more likely it is that they will choose an appropriate course of action when faced with a choice.