Speaking, writing, listening and reading are the most essential skills one must possess to be able to advance in a foreign language. Among those, writing is probably the one which requires the most effort, knowledge and skills. When it comes to foreign language teaching, you will probably notice that some students love to write essays and papers, while some despise it. Nevertheless, writing is surely one of the best ways to test or prove real skills and ability of maneuvering in a language. The teacher's job is to bring out the best in every student, enabling them to reach their full potential and the best possible level of foreign language knowledge, and that also applies to writing.
Grammar, spelling and punctuation
Most foreign language teachers think that lessons they covered in grammar are sufficient when it comes to essay writing. When writing, teachers should encourage using more complex structures, such as passive, conditionals, a variety of tenses etc. When grading essays, you should also mind that grammar, vocabulary and the essay in whole (clarity of ideas, sentence 'flow') should be looked at separately. Also, a very important thing your students should know is how to tackle the most common problem in learning a foreign language: avoiding certain grammatic structures and choosing a simplified version of what they were going to say. You should encourage them to try and use some of those structures, even if they get it wrong — practice makes perfect!
Before starting an essay writing class, you should cover extensive vocabulary related to the topic you're about to assign. That way, students can have a better grip of what they're writing about, thus becoming more able to write a high quality essay or paper.
A lesson on common linking words can be very productive, not only for writing, but all levels of language knowledge. If a student possesses great knowledge of linking words, they can organize their thoughts and ideas faster and more clearly, not only in writing, but also in speaking (conversating). Introduce your students to common linking words like firstly, secondly, however, also, yet etc. and you will see a great improvement in the way the form thoughts in the language they are learning. Once covered, a great way to practice linking words is to solve exercises which include word gaps. These kinds of tasks require a student to choose a best appropriate linking word based on the context of the entire sentence.
Arguments and ideas
A common mistake students make when writing is that they write directly on paper, without a draft. Make sure all of your students, before writing an essay, form a concept. A concept is not a draft, rather it's just a sketch covering all basic ideas in bullet points. Students often think that developing a concept is unnecessary, yet if they try it only once, they will learn how it can make their writing faster and smarter. Also, if your students are writing pro and con essays, make sure that beforehand they come up with a list of top pro and con arguments which they will include in the final version of the essay.