Well, the first listing is always the toughest one to get. You know, you don't have any leads, past clients or success stories to share. You also likely don't have the confidence that comes from years and years of navigating real estate transactions from start to finish. You're new to this, and like anything new you have to start somewhere.
That's why I always suggest that new real estate agents begin with their sphere of influence; talk to your friends, families, and coworkers. Talk to people at your church. If you're involved in community groups, let them know you're a licensed real estate professional and you're eager to help them buy or sell. If they aren't currently in the market, ask them if they know someone who is. Work through those close to you who know you as a person and trust that you have their best interests at heart.
Of course, once you get your first client you need to dedicate yourself to ensuring that they have a good experience with you. Each client can either leave the transaction as an enthusiastic promoter or a dissatisfied customer. It's up to you to convert your first client and every client into a cheerleader who will help you open doors to future opportunities.