Well for an effective poem you have to make you sure you follow all of the above.
1. Try to stay focused on a single subject or topic as much as possible. If you start writing about the sky but then talk about ice cream your readers are going to be very confused and they are not going to want to finish reading your poem.
2. Make the reader feel a strong emotion. You know you’ve read a good poem when you start to smile or tear up a bit.
3. Always use vivid descriptions and figurative language. This really helps your reader create clear picture of what is happening in your poem.
Hope this helps!!!