Brainstorm ideas for your poem
First of all, you have to brainstorm ideas for your poem. Idea acts as a milestone in didactic poetry as you cannot attract or teach your readers anything, until or unless the idea behind it worth something. Therefore, it is extremely important for you to think about something unique before starting to write the poem.
Please keep in mind that you should never limit your thinking to just few thoughts. Furthermore, if you cannot find a convincing idea to write a didactic poem, you can take inspiration from the work of other poets.
Keep your goal in mind while writing
It is very important to keep the goal of your poem in mind i.e. it must educate, inform or instruct the reader towards something. Otherwise, you will not be able to make your point to the readers and all your hard work will go in vain.
Analyse other didactic poems
If you want to improve your poetry skills, you must read the work of other poets. You don’t have to copy anybody’s work, but you can take inspiration to write your own poem. For instance, Read Alexander Pope's ‘Essay on Criticism’ provides sound knowledge about how to do literary criticism. On the other hand, Robert Frost's ‘Mending Wall’ provides good teaching about how to develop good relationship with the neighbour.
Choose the style of your poem
Usually, poems are written with two different styles namely free verse or rhyming. However, if you want to write your poem in any other specific style, you can do it. In order to build a better style, you must read your poem again and again to make the required changes.