how to recognize "good science": learn how to find peer-reviewed studies.
2) Quote good stuff. When you quote, quote "good science" rather than the words of other activists. Quote scientific studies rather than internet articles.
3) Footnote like Fury. Include footnotes or hyperlinks so that others can follow the breadcrumbs back to the sources of your information.
4) Consider the contents. Don't go just by the title alone! Read the study, particularly the conclusion. Make sure it really discovered what you think it discovered, before you quote it.
5) Tell the Truth: tell the public that "the jury is still out", that there are scientific studies on both sides of the argument. Neither side has been conclusively proven yet. GMOs have not been proven safe, nor effective. But honestly, the scientific community has not yet proven GMOs to be completely evil either; they're still working on it (list of studies), so meanwhile that evilness is merely your own opinion.
Now, whether we should go ahead full-scale as a society and bank the future of our entire food supply, the future of our environment, and the health of several generations, on an unproven technology ... that is a question of wisdom.