I feel like a beginner should know the basics of fundamental knowledge, buliding a strong ground and engouraging suitable habits i suggest gym etiquette keeping the gym clean and respectful is needed
Furthermore, I would make sure they know the importance of warming up to prevent injuries and cooling down to aid recovery. Me personally form is important in any excerise u do so i would always be sure to show them proper form to help them workout in a better action. Making sure mastering bodyweight movements before adding weights. However i would aslo add a program combining strength, cardio and flexibility exercises. The need to be consistent and gradual in your progression is important so i would teach them this aswell. Making realistic goals is important as it keeps them focused and movitated tracking progress is needed aswell as it helps you see what progress you are making in the gym. Making sure their nutrition is good as its the key importance to a good body making sure they are hydrated too. Explaining the role of rest in muscle recovery is important as it needed for better results and good sleep should be advised aswell encourage a positive mindset and introducing different forms of cardio is crucial and explaining how to use the equipment in the gym is important aswell i aslo encourage consistency over intensity as it can gradully increase the weight and intensity to avoid burnout and injury. I will always encourage the best behavour in members and they will be treated with respect and will always love to have someone making the effort to improve themselves.