Taking pictures of flowers is just like taking pictures of babies and puppies. Instead of focusing on form and the abstract qualities they can possess, pictures of flowers are lost in the fact that flowers are very beautiful in the first place. Therefore, 90% of photos of flowers end up being horribly subject driven and very boring. Which is your case. Try looking at the work of Karl Blossfeldt, Edward Weston, and other members of the F-64 group at the beginning of the 20th century. Their photographs of flowers and other naturally beatiful things are transformed into photographs of form, symmetry, and the negative space that is formed by the subject matter. Now, I understand that you do not have access to a large format camera, or studio lighting, but you can still take what they did and use it in your own photographs. Simply employing the "rule of thirds" and shifting the flower to not be in the center is not going to do much to improve the photograph. It is still going to be a picture of a flower.
Karl Blossfeldt (note how this picture seems to become transformed into a female model)
Note: Using Black and white for flower photography greatly increases the abstract quality of your images, due to the fact that it takes away the color of the flowers, which immediately transforms your subject to line and form.