First off, I LOVE being a clinical instructor. I think that is important because it is so easy to get burnt out. Not only are you dealing with difficult patients, co-workers, family, administration... but now you have the potential of difficult students. So I hope you enjoy it!
I find it helpful to spell out my expectations the first day (orientation). This is the information I spoon feed to them. What assignments will you complete, what must you have prepared prior to clinical, what are the consequences to being late, med errors, failed assignments.
I have my students prelab. They are expeceted to go to the facility the day before and look up the medical record. At home, they are to research medications, make drug cards, research diagnoses, or labs, review procedures that may come up (like inserting a straight cath, giving a SQ injection, or doing an Accucheck). I find that they are much more prepared on the day of clinical and then they are not spending valuable hands-on time working on thier care plan.
I also like to send them to ancillary departments (in the hospital). A student may follow the respiratory therapist and learn more about breathing treatments, PFTs, EKGs, and abnormal lung sounds. They go to surgery (pre, intra, and post-op). And they go to the clinic and follow a pediatrician or family practice. I have also before (on slow days) sent them to radiology to observe positioning for xrays and to view images or scans.
Overall - Challenge them! If they want to know more about a disease process or medication... make them find it and then come back to you for discussion, or have them present it to the group. At the end of our clinical day we also do post conference where we can discuss interesting cases, experience new equipment, practice assessment on each other, or work on vocabulary, math, or abbreviations. My favorite post conference activity is practice NCLEX questions. I bought an NCLEX book and I usually try to make the questions we cover match up with what they are covering in class that week. I have had good feedback from this.
Best of luck! And I hope you enjoy it as much as I do!