Start to develop your composition by planning and completing it in an ABA structure. This can seem contradictory at first because you are trying to depict ONE scene or object. Nevertheless, a contrasting middle section will give your piece more depth and will bring two aspects of the title to life.
On the other hand, if you do want to compose a piece with only one theme, go back to listen to Grieg: Schmetterling. This is a good example of a very short piece, based on only one idea, in a binary form, AB. There is no contrasting section, as found in a sandwich or ABA form.
As with every composition, you need to plan the structure of your work.