How to Email People Cold and Get A Reply

Read their stuff. It might be things on their website or their book, just get the relevant information yourself first.

Be kind. If possible, provide them with some useful information first. They have no obligation to answer you, so being kind will lead them to want to answer your questions one.

If you want a response, write shorter emails.

Don't give extra information the other party doesn't need-- "Unfortunately, I couldn't make it." is enough, no need to explain why.

Don't be afraid of having a back and forth over email.