You made several mistakes that made you look unprepared for the interview. These included arriving late, dressing inappropriately, having your cell phone ring, seeming overly desperate for the job, being unable to answer basic questions about your qualifications, badmouthing previous employers, knowing little about the company's culture, talking too much or too little, inflating your skills, not paying attention, portraying weaknesses as strengths, and treating the interview like an interrogation rather than a conversation. To improve, you need to arrive on time, dress appropriately, silence your phone, remain calm and positive, research the company, answer questions confidently, and ask your own questions of the interviewer.