But drafting a contract on your own could you do you more good in the long run, because it really make you to think what is important and what is not.
Alternatively you could hire an attorney to do that, if you will need an attorney eventually for your website.
PO Box can be used as a "mailing address". But if you used it as an office location, consumer would assume you do not have a business office.
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This is my personal opinions not a legal advice.