Webforms lessons learned the hard way (Part 1)

I've been spending a lot of my days in Webforms the last two years. In this post I want to share some best practices I've learned the hard way over these years. A lot of MVC developers might think this post comes a bit late (who still cares about Webforms?!), I do think (in the real world) a lot of the ASP.NET developers are still using Webforms. This post is directly targeting them.