If you want students to look for particular features of a paper, try having them do so in a step-by-step fashion. Students often feel most comfortable moving through a sequence from simply identifying a feature, to evaluating it, to suggesting revisions. Particularly if you give students multiple peer-review opportunities, keep this sequence in mind. Create each workshop sheet so that it builds upon the prior one. And as you design these worksheets, label each level of task clearly so that students know if they are to identify or suggest revisions as part of a given peer-review session.