When speaking about business casual attire, it means just that - professional, but casual. Neutral and dark colors make a professional but understated impression that many recruiters will continue seeking in their potential hires. In any case, do not feel you can pull out those favorite worn-out jeans, shorts or sandals to wear. It means dressing in neat attire that is going to enhance your presentation, not diminish or overwhelm it.
Body language is extremely important now and for the next decade to come.
Strong eye contact, firm handshakes, proper posture, and an upbeat positive demeanor are well received by employers and a positive start to any interview. Throughout the interview, it is important to remain enthusiastic and courteous. Always make sure that what you are trying to communicate to the recruiter matches your body movements. One thing is to say that you are interested in the position and another thing is to actually show that you are. Non-verbal communication is just as or even more important than verbal, so be aware.