for the page from Francis Drake's diary, I just used a yellow post-it note and hand wrote it in light pencil, then I used a fine-point sharpie for ink.
After that, I weathered the page.
I can't speak on how Darth Saber did it, but that was my method.
edit: I should note that the post-it works for mine due to the pocket sized journal. If you're going larger, then you'll have to scale accordingly.