Duplex ultrasonography (DU) is a useful tool to optimize vascular access care in hemodialysis patients. However, the professional training of most healthcare workers caring for dialysis patients does not routinely include the teaching of DU (in this setting), thus limiting its use. The aim of this article is to provide some practical tips, tricks and potential pitfalls of this technique, both to the trainee ultrasonographer and to the healthcare worker already applying this technique in practice. The topics covered are 1) basic ultrasound principles (physics, machines and transducers), 2) the modes needed in vascular access DU in combination with the respective ways to optimize image quality, and 3) the assessment of access flow, stenosis and access induced ischemia by ultrasonography. This is done in the format of a quiz with 12 questions and answers.