Other than what others have suggested:

• Do get an etch resist pen. The toner occasionally, even when it goes well, might not transfer on some spots of the copper plate. So you’ll need the etch resist marker to color in breaks in paths etc. and fix these little issues.
• The acid or whatever you use to etch away the copper might not work on some spots. Leading to shorts or otherwise unwanted connections. So do check with a multimeter the paths and pads that are close to make sure there arent shorts. You can scratch away unwanted copper with a blade.

I dont think theres much more to add, its quite a simple process. Have fun :)

The toner transfer method would be I think the most DIY method you can use. Make your pcbs entirely by yourself at home.

Naturally wont give you as professional a result: no silkscreen, limited to 2-layer pcbs (2 sides of a copper plate).

But it is a lot faster that having it manufactured (takes me like 1 hour for a pcb) and maybe this is debatable but it makes me feel like I have more room to make mistakes.

For the IRF1404Z, under the absolute maximum ratings, continuous drain current is given as 140A. If it was for something like picoseconds, it doesn’t seem meaningful labeling it ‘continuous current’?