I think OP's concern is related to  anonymity rather than privacy.  It would be privacy relevant if OP could have the ability to choose who can really  see his payment but  due to bitcoin design it is practically impossible  task.

As to improving anonymity (i.e. decreasing the traceability   of payment) there are plenty of ways (including those already  described in this thread) to do this, but some times, at appropriate and adequate obstinacy of investigators, all of them may fail.

Good reading an this matter - "How a 27-year-old busted the myth of Bitcoin’s anonymity".