As Mage mentioned above, practice questions. In preclinical, I used USMLE Rx and Amboss practice questions. If I could go back in time, I would substitute uWorld for Rx and continue to supplement with Amboss. The previous meta with a scored step1 use to be to save uWorld for dedicated, which is what I did at the time; however, I don't think that thought is still applicable with p/f step1.