The tough thing is that much of this comes the hard way by learning as you go. But, you can avoid this by learning from the mistakes and making a checklist or procedure for each webinar you run.

For example, I have had issues where the presenter could not get the presentation to load. So, we make sure there is a downloaded copy as well as a cloud version on ALL staff computers. We had one webinar where the internet connection could not allow the presenter to show the slides so we improvised and controlled them from a staff computer while the presenter spoke. Another issues is restarting computers a few hours before the webinar. Have you ever restarted and forgot there was a software upgrade set and it happens to install right before your webinar?!?! Yikes! Another issue is internet speed if there is a chance someone is on WIFI. Are you running a speed test before to make sure the connection is optimal? Do you have live support on the checkout page and having them prepared and trained prior to the webinar to answer sales questions? These are just a few of the things I do now as a routine for each webinar and all come from experience. I find that taking some of the advice you find here in these answers and from your own lessons, you can turn this into a procedure that you and your staff can use for each webinar. If you need help thinking through all the possible failure points, please reach out!