To start, congratualations! I hope you will enjoy nursing, it can be very rewarding. As far as clinicals, expect that you probably will be doing vital signs and assessments to start out...depends on how you'r school's curriculum is set up. You probably will do your first clinicals on a general medical/surgical floor, taking care of a variety of patients. As you progress through your first year, you will learn more skills and more will be expected of you. In your second year, you will have more patients and the expectations will continue to increase. You may (depending on your school) have a chance to do some clinical time in an area you're interested in (ie ICU or ER). Be prepared for a lot of hard work! If you can, I recommend getting a job as a nursing assistant at a hospital or nursing home. This will give you experience in dealing with patients; doing vitals, bathing them, helping them with toileting, ambulating,etc. You will be that much more comfortable when you start your clinicals if you can get a formal job in a hospital or nursing home; maybe even the ER you volunteer at could use you in a formal capacity.
If you have any further questions about anything, please feel free to contact me by email. I am currently working part-time on a telemetry floor and going to grad school to be a nurse practitioner. Take care and good luck!