Being driven by the hypothetico-deductive mode of inquiry, previous studies have tested the effectiveness of theory-driven interventions under controlled experimental conditions to come up with universally applicable generalizations. To make a case in the opposite direction, this data-driven study aims at uncovering techniques and strategies experienced teachers use in developing IELTS candidates' writing skill rather than testing the effect of externally imposed interventions. Following the constructivist grounded theory procedures, participants' perspectives on techniques of teaching writing in IELTS preparatory courses were theoretically sampled through open-ended interviews. Iterative data collection and analysis revealed techniques such as exposing candidates to sample answers, teaching grammar and vocabulary as a prerequisite to writing, teaching prefabricated patterns, raising candidates' awareness of scoring criteria, teaching discourse markers, and encouraging learners to develop their content knowledge. The findings have clear implications for both test takers who look for effective techniques of developing their writing skills and practitioners who strive to develop candidates' writing skills in IELTS preparatory courses.