I am writing to you after hearing from ....., your secretary, that your firm is considering expanding its sales staff.
Allow me to introduce myself, my name is ... Having had ... years of experience in sales and marketing of manufacturing supplies, I am confident my network of contacts in the field will be of great value to your firm. During my previous work experience, I have had close relations with several major manufacturers, which could be potential customers of your products. Accordingly, I am certain that I can increase your customer base.
I have taken the liberty of including my resume with this letter. I am confident that you will find my strengths, abilities and experience of use to your firm. Allow me to call you sometime next week to determine a convenient time to talk.
I look forward to speaking with you.