Make relaxing your body and clearing your head a bigger part of the meditation.
I have always spent about 5 minutes or less total on getting relaxed and clearing my head and then focused on the purpose of the meditation. This time we spent about 10 minutes on relaxing our body's followed by 5 minutes of clearing our head before we even began the focus of the meditation. As soon as we started visualizing I was pulled deeper into the trance and my visualizations were clearer than they had ever been before.
Rethink your meditation position.
When I do a sitting meditation I usually do it cross legged on the floor. This time I was sitting back in a comfortable overstuffed chair with my hands in my lap and my feet flat on the ground. During the meditation I did not feel the floor underneath me or even the chair. I was able to feel the water and the sand that were described by the guide.
Set the atmosphere.
Having the proper setting really does make a difference. Can you smell the garbage in the kitchen. Take it out before you begin so that it does not interfere. Place some fresh flowers in front of you or burn your favorite incense. Is the lighting just right. What is the last thing you see before you close your eyes. Are you worried that you will be interrupted because the area is not private enough. All of these things will effect the quality of your meditation.
Remember these things to help give you a deeper more satisfying experience.