What are written techniques in English?
There are so many, it'd be impossible to list them. In addition, not all sources agree on any particular ideas.
But here's a place to start:
http://grammar.ccc.commnet.edu/grammar/
Click on the Paragraph Level and the Essay & Research Paper Level menus and read the different sections. Each refers to one or more techniques used to make written English comprehensible and compelling.
Then look in the Word & Sentence Level menu. Most of the entries in here have to do with grammatical specifics, but some have to do with specific techniques, such as Modifier Placement, Parallelism, Concise Sentences, and others.