Here is a technique used in Neuro Lingusitic Programming (NLP) that I find very useful for improving visualisation skills.
Start by thinking of a good, happy memory. As you hold the memory in your mind, ask yourself how you are perceiving it. For instance, do you 'see' a moving image in your mind's eye, or is it a still picture, or like a set of still images? Do you perceive the memory in colour or black and white? Where do your eyes move to when you recall this pleasant memory, left, right, centre, bottom left, bottom right, top left or top right? Make a note of where you tend to look. As you imagine the scene before you, how far away from your body do you perceive it? Does the image appear to be up close to you, in the far distance away from you or somewhere in the middle? Do you see the scene as if you are looking out of your own eyes as the person in the action of the scene, or as if you are an unseen observer looking at yourself in the scene? Check through all these perceptions as you hold the memory in your mind and write down how you are perceiving it. This is your 'recipe' for perceiving a positive image in your mind's eye.
Now bring to mind an unpleasant, unhappy memory, and as you hold it in your mind, go through the same questions about how you perceive it. Make a note of your perceptions and notice the differences between the way you perceive a good memory and how you perceive a bad memory. Write down the differences.
Now try recalling the bad memory again, but this time change the way you perceive it to fit how you see a good memory, where your perception is different. For instance, let's imagine you see a good memory in black and white and a bad memory in colour, a good memory is close up and a bad memory is far away, a good memory is viewed when looking top left in your field of vision, whereas a bad memory is central, and a good memory is seen from the view of an observer watching yourself in the scene whereas a bad memory is seen from your own eyes as a participant in the scene.
As you recall the bad memory again, you will now change it so that you see it in black and white, move it close up to and to the top left of your field of vision, and see it as though you are observing yourself in the scene. In other words, you are using your recipe for how you perceive a good memory.
As you make these changes, you should notice that you start to feel more comfortable about looking at the bad memory. This is a good way to re-programme your view of something negative. Once you know your recipe for a good memory, use it whenever you are visualising anything. This will empower your visualisations and help to increase your success with projecting them, as you will automatically be sending them out with positive feelings.