Below is an imagery exercise you can utilize to help you visualize your intention.
Focused: A clear mind is able to focus much more then a distracted and scattered one. Therefore, you want to relax and get into touch with your breath and concentration before setting your intention. You want your intention to be that focused, and clear so that there can be no doubt or confusion as to what you want to manifest.
See yourself in it: What is your intention? Invite your eyes to close and see yourself inside the scene that you wish to happen. You can imagine seeing yourself in the exact surrounding and situation that you would like to happen. If other people or things are there, you can bring these into your image. Really allow yourself to be there and then your manifestation can become real.
Action: Once you imagine the scene happening, try to create action in your mind. If there are people, they can be moving, talking, cheering, smiling. If there are no people, see yourself in motion, get some feeling into this mental movie and make sure you can actually feel the motion in your body, that is one sign that your body is going along with the imagery you are creating.
Multi-sensory: Because life is perceived through all of the senses, your image should mimic real life as much as possible. Therefore, if your intention is to have more confidence before your big meeting on Friday, Friday morning you should wake-up feeling competent, confident, and knowing that you can do it, you might see yourself with your imagined result, and lastly get in touch with the success of your most desired outcome. What does that feel like in your body? What emotion is behind it? How does this make your life better? The more senses are involved, the stronger the intention will be.
Time: The frequency with which you repeat this meditation will also determine the speed with which it manifests itself. Imagery is more powerful the more you practice. Running through this exercise for the first time may take a while, but once it is well formed it becomes easy, quick, and much more clear. The power and effect increase dramatically with every repetition similar to practicing any other skill, the more you do it, the better you get.