Generally, whenever you think "control", instead think "command". You've come a long way now...
cmd+q = quit. cmd+w = close window. cmd+n = new (window of whatever is relevant).
You have a global application menu up top like Unity used to have on Ubuntu. The Help menu has a HUD kinda deal where you can type in whatever you're looking for and it'll show you where it is and what shortcut it has. Like in Safari, if I hit Help in the menu bar, then write "private, it will show me that "New private window" is cmd+shift+n and is found in the File Menu. I can also just hit it from the Help menu.
cmd+tab gives you an app switcher row, but more useful in my opinion is spaces. If you want keyboard navigation instead of trackpad gestures (I rely on both), ctrl+arrow left/right changes space left or right. Arrow up with control goes into Mission Control (workspaces overview with applications per workspace, including fullscreen spaces), and down arrow (this may need to be enabled first) goes into App Exposé; That is, all open windows for a specific application (inside App Exposé, ctrl+tab will cycle between applications in that view).
CMD+Option+Escape brings up the force close menu. You probably won't need that but if you do; That's your "control+alt+delete".
I have my Macs all set up with iTerm 2 in a drop-down terminal way, where when I hit cmd+shift+enter it pulls down a Terminal rom the top like this
Not a general macOS thing, but if you are a user of the command line coming from Linux it's very lovely. I can hide it again with the same command and it can be pulled down on top of anything, including fullscreen games.
cmd+space opens Spotlight. Spotlight is amazing. At first glance, it's a search field. You can search up files and folders and such, based both on title and content. So if I have a big PDF that says "Hello there Bob how are you?" on page 704, I can search for that phrase, and Spotlight will find that PDF. But Spotlight can do a lot more too. Type sqrt(cos(pi*4)) into it, and it will tell you the square root of the cosine of 4π. Type 100USD in CAD and it will tell you how much 100 US dollars is in Canada bucks, and so on. Also has dictionary and a bunch of other features.
All shortcuts can be view in System Settings under keyboard -> Shortcuts. You can also define your own shortcuts for any application in there. If the app has a feature that can be used through the menus in the Menu Bar the global shortcut system can be used to trigger it.
By default, F11 (hold fn keys if you have them setup to use media keys without FN being held) will show you the desktop, F11 again brings all your windows back. The is a spread gesture on the trackpad.
CMD+H hides an application and all its windows. CMD+M minimises it. I never minimise, I always hide.
If you have any specific queries I can provider further details but that's a quick list of some of what I use the most. Oh and an important one I forgot; The extensive and awesome screenshotting capabilities
CMD+Shift+3 = Fullscreen screenshot; Saves to your selected screenshot storage location. Appears in the bottom right for a while before going into storage, where you can click it to edit fast or send it somewhere else (or drag and drop the image)
CMD+Shift+4 = Enter Area-Screenshotting. In this mode, dragging over an area screenshots just that region, but otherwise in the same manner as above.
When you are in Area-screenshotting mode, clicking the space bar will enter "Window screenshotting" where you instead select an entire window to screenshot.
CMD+Shift+5 = Enter Screenshot menu. From here you can change settings like where screenshots are saved, if there should be a countdown before the screenshot is taken, etc. You can also do screen recordings from in here (both region and full screen), and select audio recording (microphone selection) for screen recordings, and whether or not mouse clicks should be highlighted in the recording.
For any of the above you can hold CTRL as well to bypass the saving to storage and image in the bottom left, and screenshot directly to your clipboard.
Coming from Linux, I recommend you installing home-brew. It's like apt for macOS so you get a package manager. If you are also familiar with BSDs MacPorts is also a good choice; It's like FreeBSDs Ports system. There's also Fink which is more of a direct port of apt, but it's not got that big or updated repos. Homebrew is more widely used, including by Apple themselves.
A few more I thought of last minute:
CMD+Option+D hide and show Dock
FN+A = Keyboard selection of Dock items
FN+C = Open Control Center
FN+N = Open Notification Centre
If you have Full Keyboard Access turned on, and menu bar navigation is also turned on (FN+CTRL+F1 turns that off/on)
you can use CTRL+FN+F2 to enter the left side of the menu bar and CTRL+FN+F8 to enter the right side of the menu bar
To quickly turn on/off Full Keyboard Access or any other of the main accessibility options, hit CMD+Option+F5. This brings up the "Quick Accessibility Options" menu. For more detailed options on each one, see System Settings.
With Full Keyboard Access on, and any app focused, Tab+H gives help info on keyboard navigation within the selection, and Tab+A brings up a focus-selector.
Hope that helps
