I know it sounds cliché, but make it thrilling! That means page one, line one. Something important has to be happening on page 1. Something critical to the character or the plot. I can’t tell you how many manuscripts I’ve looked at that don’t have the action actually start until page 10, or 30. As a reader, I don’t give one whit what the hero/ine had for breakfast, or who their family is, or the boring day they had. If they are meant to witness a murder or wind up at a bank robbery or get slipped a flash drive full of secrets, then THAT’S what I want to see on page 1!