I was struggling with this for the first couple of days and was starting to get pretty frustrated with it, but then I figured out an easy way. The way I’ve been doing it is that I open the iPad like a book from the keyboard half until it locks in place, and then I set it down on whatever surface I’m using it on and adjust the angle the rest of the way from there. Seems to work out well and avoids the issue of the iPad sliding around on the table/desk and making it hard to open.