The acquisition of representational competence is a central challenge in chemistry education, as students must learn to read, draw, and translate between multiple structural notations. Expert chemists fluently navigate molecular formulas, Lewis structures, skeletal formulas, and three-dimensional projections, yet novices often struggle with the conventions and underlying mental models required. This study investigates chemistry teachers' perceptions of students' typical difficulties in structural representation and their strategies for support. Drawing on survey data from n = 116 teachers in Switzerland, Germany, Austria, and Denmark, complemented by follow-up interviews, we examined (i) when teachers expect students to interpret and generate representations, (ii) which compounds are used for introducing notations and diagnosing errors, (iii) common mistakes observed, and (iv) instructional approaches to address these challenges. Teachers reported introducing sum and condensed formulas around grades 9–10, while more abstract notations such as skeletal or wedge-dash structures are expected later. Frequently used examples include simple alkanes, alcohols, and carboxylic acids, chosen to reduce extrinsic cognitive load. Typical errors include violation of the octet rule, missing or excess atoms, and incorrect spatial orientation, especially with stereochemical drawings. Interviewed teachers emphasized scaffolding complexity, repeated practice, and the diagnostic use of simpler molecules to surface misconceptions. Some highlighted the potential of Augmented Reality and adaptive feedback to strengthen spatial reasoning and individualized learning. These findings underscore the need for innovative educational resources and teacher-informed design to better support representational competence in upper secondary chemistry classrooms.