First and foremost, follow any of the rules you are given. Think of your clinical instructor as your supervisor. This person is going to be evaluating you as well as giving you instruction. So, if they give you a direction, follow it. The biggest reason people fail clinicals is because they don't do what they are told or they do something that puts a patient in jeopardy of harm. That includes things like sitting a patient up on the side of a bed and then turning your back and not paying attention to them while doing something else, or walking out of the room. When the patient falls on the floor it's the student's fault for not looking out for the patient's safety. The same goes for forgetting to pull up the siderail on a confused patient after putting them back to bed and then they roll out onto the floor.
You will usually get some sort of orientation to a facility on the first day you are there. That includes a quick run down of where the important places are that you need to know about and how things are generally run. You're not supposed to remove charts from the area where they are generally kept without letting someone know you are doing so. In an acute hospital, the charts are looked at pretty frequently so they need to be available to everyone.
Don't be afraid to ask questions and volunteer to do things. Instructors take note of this. They also take note of students who don't ever volunteer or show initiative. I've often posted that the evaluations of clinical instructors go into student files and are referred to later when students need recommendations for their first nursing job. Employers of new graduates aren't so much interested in how many procedures you have done because they know you lack that experience. They are more interested in your character and what kind of employee you will be. So, you want to always have a positive outlook, act responsibly, be flexible, show initiative, demonstrate that you can work harmoniously with others and can show some leadership when the situation calls for it.
Also, carry at least two pens (in case you lose one or a doctor walks away with one), a small notebook that you can jot notes down on, a pair of bandage scissors, I always had a pair of hemostats as well, and enough coins to buy a Coke when you go on break.
Don't be concerned about your age. My mom went to LVN school when she was 50+ and worked as an LVN in California and LPN in Ohio until she was 68 and they practically had to throw her off the job! You've got life experience on your side. I'm sure you'll do fine. We've all been through these first day jitters. As a nursing student I used to get nauseated as I walked into the hospital for my clinicals because I was scared to death of accidentally doing something that might kill someone. It was years before I was able to overcome that fear. And, still, I would step forward and volunteer to do things because I wanted so badly to learn and to gain the experience. Well, it's been 30 years and I haven't killed anyone yet.
See you on the student forums! Welcome to allnurses!