If you don't have work experience you just have to keep applying. Getting a job sucks in this economy but there are still jobs out there. Also, double check your resume and applications to make sure there are no glaringly obvious spelling and grammar mistakes.
When you first go in, shake hands with them and always show excitement to the one interviewing you and SMILE. Anyone who can get a job these days SHOULD be excited. Show interest in the company you are interviewing for. Make sure they know you would go up and beyond the call of duty to do a good job for the company, that you want to be a good representative, and if they show interest, ask them how you could do that. Be outgoing and just show interest and excitement. Make sure you shake hands at the end and taking the time to interview you.