Wedging branches diagonally is what I do too, & yes, I use natural branches from my trees. You can't buy them as big as I need-I also use short pieces of covered "speaker wire" (very strong & flexible- NOT "Monster Cable" or anything like that- I mean the older, narrow stuff I have on hand) to twist around them where they cross each other if needed for stability- it's easy to un-do or re-do. Zip-ties work too, but you have to cut them off. I think branches are easier to install if your enclosure opens on top- not in front- btw.
In my largest tanks, the branches* only go in (fit) one or maybe two ways- sometimes when I clean late at night, it's like a puzzle trying to get them back in when I forget how I had them.*I often use 3 branches per tank- sometimes 4- and they're not straight "boring" branches either. But rat snakes love branches & I aim to please. You can also use a few bits of coated wire to attach a flat or shallow "basket" to such branches, to be used as a shelf by your snake. Snakes love those too- & woven baskets also have more traction than a flat "shelf" like some ppl install. You can find & buy such baskets very cheaply in thrift stores- & btw, I wash them off, & spray with the same chlorhexidine I wipe tanks out with. Dry before installing.