Answer all competency based questions without any silly spelling errors and make sure the answers are strategically constructed so as to follow the scenario, context, action and results format. The SCAR format will go along way in helping you to set up your answers in a way that they would flow out without any mix ups and most importantly you will have to remember the answers you have give as you may be required to give those answers again in during the face to face interview. Also, stay positive as being positive will radiate through your voice, believe it or not.