If you have a cluttered Desktop, you may want to occasionally hide the icons. You can do this with third-party apps or Terminal commands. You can also write a very simple shell script in Automator and save it as an app. Then you can toggle the Desktop on or off with a simple click in the Dock.
If you use the Find function in the Finder you can perform file searches that are much more complex than using Spotlight. You can add many pieces of criteria to the search other than a single search term. If you know how, you can use logic to combine search criteria and add very specific options. Then you can save your searches so you don't have to recreate them from scratch later.
Many Mac users ignore the Go menu in the Finder, but there are some useful shortcuts there. You can access some of the most most used folders on your drive with this menu and see keyboard shortcuts for them. You can also access your Librray folder and Startup Disk through the Go menu if you know how. The Go to Folder function lets you move around by typing, which is preferred by many pro users.
You can customize your Finder sidebar to include the folders and locations you most often use. You can click on a sidebar item to go to that location, and also drag and drop items into those locations. You can customize the sidebar in Finder, Preferences, and also by dragging and dropping items into and around in the sidebar. Tags and Smart Folders can be used to make the sidebar even more useful.
It is fairly easy to compress a single file or multiple files and folders into a ZIP file archive on your Mac. You can also decompress any ZIP file by simply double-clicking it. This is useful for sending files online or to store files you no longer need. The Archive Utility is used invisibly for both commands, but you can run this app by itself and choose from more options when compressing or decompressing ZIP files.
Instead of storing your videos in the Photos app with your pictures, consider storing them as files in a folder in the Finder. You can place this folder on your iCloud Drive, on your local drive only, or on an external drive. You can organize them using file names, subfolders, tags and comments. You can use the Gallery view to look through your videos almost as if they were in a special video management app.
There are many ways to customize how files and folders appear on your desktop. You can manually arrange them, or have them sorted automatically. You can change the size of the icons, the text, and the grid spacing. A new feature in macOS Mojave is to have similar files organized into stacks. You can also select what other icons, such as hard drives, appear on the Desktop.
If you need to print the list of files in a folder, you can do it using TextEdit, the Terminal or by using a special trick involving your printer. Using TextEdit is a simple drag-and-drop, but you must be working with a plain text document. By using the ls command in the Terminal, you can customize which information is included with the listing. You can also simply drag and drop a folder to an alias to your printer, but you must create that alias first.
Need to convert a jpg image to a jpeg? Or an mov video to a mp4? Chances are you don't need to convert anything at all. You just need to change the filename. File extensions on a Mac are somewhat optional and often interchangeable. A jpg is the same as a jpeg file. Video files extensions aren't as important as the contents of the file as video file are really just containers.
It is common to hear a Mac user complain that the file search function in macOS Finder doesn't find files they know are present. The reason is often that the user has made one of these mistakes. When searching for a file, the search usually starts in the folder in which the user is currently looking. You need to change the scope of your search to look elsewhere as well. By default, searches look in the content of files as well as the file names, but you can narrow your search to only the file names. If you are looking for something other than a file's content or name, you need to start the search differently. Many users search for files using Spotlight, but if you know you want a file, then it is better to search with the Finder.
A common complaint from Mojave users is that when you copy and paste a file icon to create a custom icon for a file or folder, the result is blurry. It turns out that this only happens when the icon image is not square. Convert the image to a square one, or copy a square portion of the image, and the result is crisp and clear.
When you save a file you get to assign a name and pick a location. The standard save dialog provides a lot of power user techniques that most people don't know about. You can harness the power of Finder windows to choose a location, you can use keyboard shortcuts to jump to locations and cancel. You can click on existing files to inherit the same name.
The Open With command makes it possible to open a file with something other than the default app. But if you commonly need to do this with a specific app there are three ways to make it much easier to open the file with that app instead of the default. You could just drag it to the Dock icon for the app, add the app icon to the Finder toolbar, or create a keyboard shortcut.
Prior to High Sierra there was a Finder sidebar item called All My Files. This showed you a big list of all of your documents. This was replaced with the Recents list, which only shows documents you have opened and leaves out files you have created or downloaded, but haven't opened yet. You can easily re-create the All My Files list by making a Smart Folder and adding it to the Finder sidebar. You can customize this Smart Folder to better fit your needs.
The new Gallery View in Mojave allows you to see file data for the file selected. You can choose to show more or less of this data. You can also customize this data to pick which items are shown by default. This function isn't for the Gallery View only, however, as you can also see it in all four Finder views.
A new feature in macOS Mojave is the ability to edit and manipulate files directly in the Finder using Quick Actions. You can rotate and mark up images, mark up PDFs, trim video and audio, and even convert images to PDF files. In the future you will be able to do more with third-party extensions. You can currently build your own Quick Actions in Automator too.
A new feature in macOS Mojave is the ability to temporarily group files on your Desktop into Stacks. These Stacks can contain files of a similar kind, or groups organized by date or tags. You can expand and collapse any Stack to see what is inside, and use the file icons inside the Stack like regular icons. Desktop Stacks can help if your Desktop gets messy and you need to find files right now, but don't have time to organize your Desktop files at the moment.
The new Gallery View replaces Cover Flow View in macOS Mojave. It is useful for flipping though a folder full of images, PDFs or other document types when you need to find one using a large preview image. There are some customization options for Gallery View.
Quick Look gives you the ability to view the contents of files without needing to open them up in an app. You can easily view a single photo or document by pressing the spacebar. You can also page through PDF files or view groups of photos. If you open up the Quick Look window you can continue to select different files with the cursor or arrow keys and the window will reflect whatever is selected.
When you look in List View in the Finder, you'll see a file size for every file, but no size listed for any folders. You can still view the total size of a folder using one of several methods. You can Get Info on a folder to see the size and number of files. You can also use the File Inspector. Quick Look also displays the folder size. If you want to see the sizes of all folders in List View, you can enable that by changing a setting.