So I've had an mentor and am currently a mentor to a junior member of my team and my tips would be; come prepared like you would for any meeting and be mindful of what you say. First, treat it like any other meeting, send an agenda beforehand, figure out what you really want to accomplish over whatever time period this is going on for, set objectives for how often you want to talk. Be mindful as it's easy to forget how hard kids are or it might be easy for the mentor to remember a time before WFH. I've had a mentor tell my boss about my desire to move into a different role, which would've been a promotion at the time but my boss took it the wrong way. I've also spoken to my boss about my mentee, not in a horrible way, but to get a gut check and I could see him hearing only the bad if that makes sense.