I always worry a bit, as I mentioned in the beginning - this after maybe eight batches so far and not a bad beer yet. It's just my nature. The guy who I buy my supplies from gave me two pieces of advice when I started out. Remember that it is only beer, and santize everything. Those have held true.
Edit - note that this thread is a month old - I have traced my most recent batch from its beginnings. No angst now that it is done.