Word of mouth advertising is really no more than consumers providing information about you to other consumers. As a travel consultant, you know the value of a good reference. Smart word of mouth marketing encourages and gives people a reason to talk about you and your services. While word of mouth marketing happens with or without your participation, you can encourage and facilitate it.
One of the most important ways to facilitate word of mouth advertising is to actively ask for referrals from your existing clients. Give your happy customers a way of easily describing your services to others. Provide two business cards to each of your clients: one for them and one to pass along to someone else. Small brochures on you as an individual (even as an employee, you are a brand!), your practice, philosophy, your assets as a travel agent also work well.
Go ahead and ask for the referral. Most satisfied clients are happy to do so. Then, facilitate the process by making it easy for the client to pass along the good word!