I was in the exact same boat you're in, Km41566, only it was last year at this time for me. I was in a new clinical site, doing 12 hour clinicals (after having only done 6 hour clinicals the semester before) and I had an instructor that could easily intimidate me. I was a wreck every time I went to do an assessment! I had a really hard time coordinating my pt's care - every time I went to do something or assess something, something else would come up and I would have to wait and I'd never get back to it. That semester was really hard, but thanks to that instructor, I learned A LOT! I couldn't believe the amount of information I learned that semester.
Now, I'm in my last semester of my ADN program, and assessments don't scare me anymore. (See, it does get easier!) You just have to think of it as any other "normal" part of your nursing care. I also used to prepare and prepare for clinical day, but I found that being overprepared, trying to stick to the plan was a lot harder than doing things as they came to me, and you develop your own style after a while.
It all boils down to how you deal with people - when I go into a patient's room for the first time, I introduce myself as a student nurse and tell them I'd like to take care of them today if that would be okay with them (this kind of gives them a say in their care, and nobody's ever told me "no, you can't take care of me"). Then I just talk to them for a few minutes about whatever - something on the television at the moment, about the flowers someone sent them, about the weather, whatever. Then I tell them a little about what I'll be doing today - bath, linen change, assessment, and whatever else they need. I think this kind of thing puts the patient more at ease, and it'll put you at ease with them.
If you're not a really social person (and there was a time where the thought of going up and talking to someone I didn't know scared the pants off me) - just do what the others here have suggested. Something I do: whenever you're checking out at a store or paying the bill at a restaurant, tell the cashier hi and when you're leaving, wish them a nice day. I used to work in retail and got into the habit of doing this, and it's really worked out well in my clinical experiences. And, it'll make you more comfortable with people in general, it'll make you feel good, and it might make somebody else's day a little bit better.