To make the head board, I started by joining the boards using biscuits.
I wiped most of the glue squeeze out with wood dust right away, then once dried I went over with a chisel and a hand plane to remove the rest.
I used the orbital sander with 80 and 150 grit to finish the surface.
Then I trimmed the ends to the final length with the jig saw first...
...and finally with a router to leave a perfect finish.
I always make lots of adjustments to the initial plans throughout the build...
To cut the miters for the head board frame, I used the miter saw. To get a bit more accuracy I used a piece of sacrificial plywood as the base so it'd show me the cut line. Then I sneaked to the cut line a little at a time.
I don't trust the guides on the saw, so I made a few test cuts on scrap wood to make sure I got a perfectly square angle:
The frame is also joined with biscuits.
A handy trick to clamp very long boards is to connect two long clamps:
This is how the back of the head board looked like once done:
If there're any small gaps in the corners I finish them with a mix of super fine sand dust and glue:
The side boards were a lot easier to make, here's a gluing the rail to it, which also has a bunch of drywall screws:
Then to length on my sled:
These are also glued with biscuits. Here's using Matthias Wandel's trick to remove squeeze out with wood dust: