Information and hints for candidates
Basically it is not necessary to prepare oneself to an assessment. Certainly it helps not to appear in a very tired or otherwise abnormal condition - however, if this should be the case, mention any specific information about the current situation to the assessing person. It is important to pay attention to questions, to follow instructions and to present oneself in a normal, authentic way, therefore not to "play a role" by trying to appear differently or "better" than reality. This intention or tendency is called "impression management": the higher this value appears in the analysis of tests and behavior, i. e. the more one tries to fullfill a real or imagined expectation, the less become authenticity and credibility.
It is helpful trusting to professionalism and experience of the assessors. If this should not seem to be the case, don't hesitate to ask questions and to inform, in an appropriate way, the assessors as well as the person who sent you to the assessment, about uncertainities or personal impressions.
This is an extract of the book "The prognostic Assessment" from Thomas Baumer (in German).