For those aspiring poets who are just beginning, and even for seasoned veterans, the tanka is the perfect poetic form for practicing description and imagery.
The tanka is very similar to the Japanese poetic form known as a haiku, but it is slightly longer. A tanka consists of five lines with the following syllable pattern: 5, 7, 5, 7, 7.
A typical tanka poem has a subject that either relates to nature or emotions. These are not the only subjects that can be used for a tanka, but they are by far the most popular.
When writing a tanka, keep in mind that you're restricted by a very tight syllable count. Five or seven syllables per line are not a lot to write a complete poem with. That is why many people recommend using tanka to practice using only important words. With a poem as short as a tanka, it's important to omit unnecessary words and only use those that benefit the description.
Another important aspect of the tanka is that it relies heavily on personification, metaphors, and similes. The tanka poetic form is all about description. The purpose of it is to project a certain scene or image to the reader, so every word must be chosen carefully to match that image. For this reason, figurative language is very common because it's easier to compare the scene to something else that is well known than to describe it in more detail. For example, in a tanka about night it might be wise to say “stars burn like headlights” to mean that they're extremely bright and blinding.
The most important thing to keep in mind when writing a tanka is that every word matters. Because the form is so short and concise, it is extremely important to use powerful words. This is why many poetic forms teachers have their students write in tanka or haiku exercises. With limited space, it makes poets think more about what they're saying; they have to pay attention to how each word contributes to the desired image.
The words you'll want to use in a tanka should be as strong as possible. If you need to use a thesaurus then do so, but if you can think of an alternative to a word that sounds stronger then use it! For example, use struck instead of hit, crash instead of fall, etc. These words evoke stronger emotions. Little changes such as these can make a big difference when used in a poem.