When you know the recipient’s name, sign it “Sincerely yours” or just “Sincerely”, or in the US “Yours truly” is acceptable. Don’t try anything more cutesy or friendly unless a) you know the recipient quite well and are certain you can be informal without seeming disrespectful, or b) you have a “trademark” letter ending that’s part of your public persona (and the talent and popularity to pull it off). Signature and printed name: Signing your name is a minimal assurance that you stand behind what was written.
However, before using a general salutation (or leaving off a salutation), try to find out the name of the person you are contacting. If you are applying or inquiring about a job and the hiring manager’s name is not included on the job listing, you might look up the title of the employer or hiring manager on the company website. If there is a contact number, you might also call and ask an administrative assistant for the name of the hiring manager. If you are sending a different type of letter, you can still look up the person’s name on the company website, or speak to an administrative assistant or contact at the company for the name of the person you are trying to reach.