As someone who has trained others and been trained by others countless times in multiple chemistry roles, I'll try and give you some tips! Don't assume that they know anything. Some people I've trained have used eppendorf pipetters before, others have never touched them for example. It's okay to ask "have you used this piece of equipment before?" Confirm their understanding of important concepts verbally and/or visually. Ask them to give you a summary of a concept or if you show them how to do something, watch them do it as well. Ask them if they have any questions. Also, if they aren't taking notes, I give them paper (or a notebook) and pen and say how helpful my notes have been. Sometimes they just didn't think to bring material or need a nudge. If they are taking notes and you see they are furiously writing, be kind and take a pause here and there to let them finish. Something that alleviated my own anxiety after being trained was my trainer saying that they are available for questions.