Good answers to employment assessment tests are those that are as honest as possible while still presenting the employee in a positive light. If the test asks whether the applicant is helpful and friendly, it is a good idea to answer "Yes," even if the truth is more nuanced.
Applicants are advised not to over think their answers on the test and go with their initial instincts on most questions. For example, if the test asks if the applicant has ever stolen anything, the applicant may be inclined to answer "No," but, upon reflection, remember a small piece of candy she stole when she was a toddler. Since the test generally doesn't allow applicants to explain or clarify, a "No" answer to this question is still acceptable and a good idea in this case.