If you are familiar with iOS devices, macOS should seem pretty familiar. Sure, there are a lot of differences, but many concepts carry over between the two OS.
Use the forums, like this one. Ask questions, but be humble and offer that you are new to the OS and folks will be exceedingly helpful.
Make use of Google searches such as "X alternative for Mac" where X is a Windoze program you are looking for a Mac version of, many developers have both Mac and Win versions of their apps, but for those who don't, there are plenty of alternatives. Use the App Store primarily (for safety reasons) until you know who the trusted developers are.
Don't sweat Anti-virus\Malware too much, it is still relatively uncommon to see security issues with Mac. But, don't entirely neglect security. Many users swear by Malwarebytes, I have not used that in years but do use the free Sophos app.
If you install apps you find you don't want to keep, search for an uninstaller that comes with the app, sometimes it is contained within the .app bundle. Officially, you will be told to simply drag the .app bundle to Trash, but this is not a clean uninstall as described below.
Apps are stored in a .app bundle (think of it like an executable .zip file in a way) in the /Applications directory. Don't try and get fancy and install apps in other locations, it will eventually lead to heartache. To see contents of an .app bundle, right click on the app icon in Finder and select show package contents. If there is no uninstaller for the app, consider some free or low cost utilities like AppCleaner. While some apps only use the .app bundle, many put resources in a few other locations. To completely clean up apps you no longer use, AppCleaner will search for these other files and offer to remove them for you.
If you have an Apple Store near you, find the free workshops they offer and use them. Repeat workshops, the instructors tend to have a rough outline but will tailor classes to questions users have. So, others in your class might bring up topics that you have not thought about and are not on the specific agenda. That is ok, because you will keep learning every time you go to these classes. And it will give you the chance to bring up your own questions and get expert advice, the instructors are often quite knowledgeable, generally well more versed than the "Genius Bar" techs.
Be patient, and enjoy the learning curve. Sure, at first you might feel a wee overwhelmed with new stuff. But in the end, computers are computers. Many of the things you can do on Windoze are possible on Mac, but with differences in most cases. Within a week or two, it will feel pretty natural, within a year, the curve will flatten and you will be very comfortable.
If you are technical, familiar with Unix\Linux, you will find the Terminal app is your gateway to all kinds of fun. MacOS is fundamentally a Unix based OS (BSD), but departs from it's Unix underbelly in many ways. Many *nix command line utilities are unaltered, or only modestly modified on the macOS platform. But, the file structure of Macs is a tad different than the *nix filesystem. Learn the file system if you are going to go down to this level.
Have fun learning in your new reality!
