I want to answer this generically, without going into specific areas of expertise etc. So:Be presentable.Be articulate.Be able to get up to speed on specific issues very quickly, and hold an intelligent conversation around them.Be able to offer sound/reasonable advice based on imperfect knowledge, past experience, and a wider knowledge base.Pretty vague, I know, but these skills also serve people well in senior industry positions - hence why many top businesspeople have been consultants at some point in their lives.A lot of people will answer 'do powerpoint', 'kiss ass', 'work 5,000 hours every weekend' etc., but the best consultants are the same as the best people in any industry/profession - practical and sharp - this is what clients value.Feel free to disagree!