I was wondering how other people are organising their assets for individual posts when using Jekyll. For example, if a post has an image, do you just dump it in a shared images
For JavaScript and CSS, you may want to consider an asset pipeline. You can get a good performance improvement through bundling and compression. I also use CoffeeScript and Sass, so I needed a preprocessor to convert my assets. I use Jekyll Asset Pipeline to manage this whole process automatically when I run the jekyll
command.
For images/video, I recommend you develop a convention for naming folders in your project. I generally have an "assets" folder then subfolders with the date of each post that holds the images related to those posts. If you have multiple posts per day, you might consider including the name of the post.