Ask permission first
Double opt-in is the gold standard: check with both sides before connecting them. It respects everyone's time and dramatically increases the chance the intro turns into a real conversation.
Lead with context
In your intro message, say why these two people should talk and what each one does. One or two sentences of context is worth more than a long bio.
Then get out of the way
Once you've made the connection, step back and let them take it from there. Your job was to transfer trust — now let the relationship form.