Writing skills don't have to be difficult. In fact you can download some fonts for MS Office where it shows an outline for students to practice their writing skills. There are some other activities for writing as well.
The most popular writing activity is to show a template for writing (such as a resume, a postcard etc) and get the student to read the text. Highlight any words that are unknown for students. Next brainstorm vocabulary on the board, related to the text, to get ideas flowing. Show another example piece of writing and let students read the second text alone.
Finally, tell students that they must complete a piece of writing associated with the text you have shown. I like to do movie reviews (after watching a particular movie at the cinema etc) and post cards (try to get children to make the postcards) with students.
There are a number of photocopiable worksheets available for teachers of adult and young learners. I recommend you fork out the money to buy these materials as they will save a lot of preparation time and you can then get a library for your own personal use for students.
Primary Communication Box Primary Grammar Box Primary Pronunciation Box Pronunciation Games Primary Vocabulary Box Primary Reading Box Reading Extra Speaking Extra Writing Extra Listening Extra
Hope that helps.