I highly recommend you come to tutorials / practicals prepared, having already done the readings and are familiar with the lecture / textbook. Knowing what you are talking about and having questions / ideas will help. I'm not just talking about participation marks- but it will help with motivation, essays / exams, presentations, etc. So be an engaged student.
Like others said, a uni class isn't a race where you have to be 'ahead'. What's important are your organization skills (summarizing notes, keeping tabs on assessments due). Sometimes it's about also being smart and dilligent- not being afraid to ask questions when you are struggling or confused (because that will happen. No matter how prepared you are, you will eventually feel lost)
If you have time, and want to read further within the textbook- go ahead! But make sure you understand the key concepts prior to doing that.
Good luck.