I usually just check, re-check, check again, check to make sure, email the details to someone to ask them to check that I've not done anything stupid, check one last time, click the payment button, then check the resulting screen. After that I check the confirmation email, forward that to someone else to check, and then check their response. Finally I check the confirmation email and the itinerary page the next day, the day after that, each day before setting off, and in hourly increments on the day.

I wish I was joking.