Make your resume and resume differ from those of other candidates. As such, you should never start your resume with such general salutations as dear sir, or dear sir. Normally, when a company posts publicly a recruitment ad, it will surely address the name, address and contact number so as the resumes may be sent to correct address.
Do not forget to end it with promising sentences that you are ready for the interview and if there is chance and will actively contact the employer before he or she contacts you. This way will help impress and smartly remind the employer of you. And also, do not forget to put your name, address, e-mail and phone number at the end of the resume or resume.