No idea re high money divorce but generally speaking:
Don't waffle - nerves and heightened emotion can make us blether on or at least I'm like that - it's a waste of their time and your time and money
Prepare the key points you want to discuss written down so you remember to mention them
Make your own notes during the conversation also allows you to not interrupt their flow but note questions that occur to you from what they say
Use the meeting to assess if they are competent, assertive and proactive
My first solicitor was dreadfully slow and passive and I stayed with her far too long, 2nd was much more on the ball and more determined on my behalf (ex was dragging it out to avoid marrying ow)
Stick to pertinent points - I made the mistake of treating first like a therapist - which suited her fine as I was on legal aid (you could still get it for divorce then) and it let her bill lots of hours! Without actually doing any work! 2nd solicitor addressed this issue with me early on, pointed out it served neither of us really and that she also wasn't qualified to act in this way and she didn't want to run the risk of making it all harder for me.
Don't be afraid to ask for clarification or address things you're unhappy about
Eg both solicitors were imo poor at acknowledging that my priority was dd and being more stringent with ex on those matters that mostly affected her.
Don't call/email them every time you think of a query, wait till you've a few - again time/money reasons but also sometimes it's good to mull on a matter before demanding solicitor does something
Hope that all is genuinely helpful