Choose the poem that you want to parody, and make sure that you have a clear idea of why you want to parody it. Possible reasons for parodying a poem are to critique its message, to poke fun at its style, or to force people to look at a familiar issue from a different perspective.
Study this poem closely. First, determine what the poem's message is: What is the poem trying to say? Write this down.
Study this poem further. Figure out if it has a regular rhyming pattern, if it has a regular meter and rhythm (or how many syllables it has per line), and, if there are multiple stanzas, figure out what each stanza is doing for the poem's message.
Determine when your poem was written and try to figure out what words that appear in your poem are no longer in use. Also try to figure out if words that are still in use have the same meaning in the present as they did at the time of the poem's original writing.
Take the information from step three and figure out what kind of poem it is. Terry Clitheroe's website, "The Poets Garret," is a good resource for different poetry types (Reference 1). If you cannot find a type of poem that matches the rhythm, rhyme scheme, and stanza use that you have determined your poem to have, then try running a search on the title of your poem with an online search engine.
Find the key words of the poem. These key words are those that are the most important for the poem's message, its rhyme, its rhythm, and its form. Make a list of these key words.
Find the key lines of the poem. Key lines of the poem will be those that convey images or ideas that are essential to the poem's message. Make a list of these lines and describe what they do for the poem. If the poem that you are working to parody is particularly short then this step may be skipped.
Change the message of the poem into an inversion or ironic version of itself that fits with your reason for parodying this poem. Make sure that the altered message of the poem will still fit into the rhythm, rhyme, and sense of the poem that you have selected.
Change the key words that you have found to suit this new message. Make a list of these changed key words.
Change the key lines of the poem to suit the changed message that you have decided upon. Make a list of these changed key lines.
Switch the key words and lines of the original poem with your altered key words and lines. This can be as rough a replacement as you need it to be, do not worry just yet if the words and/or lines that you have chosen as replacements do not fit the rhythm or rhyme.
Work through the altered poem line by line, making changes to words and, if necessary, word order to make your alterations work for the form, rhythm, and rhyme of the poem you are parodying.
Confirm that all of your alterations fit to the form, rhythm, and rhyme of the poem that you are parodying.
Ensure that your alterations come together to make the altered message clear.
Distribute or publish your freshly finished parody poem as you see fit.