Macs still don’t have the issues that Windows has with malware. That said, there are efforts to target Macs. So here is what I recommend and what I do:
1. Use the latest OS your Mac can run and do the updates Apple sends out. This will take care of 90% plus of the malware issues.
2. Install *Little Snitch. Just the presence of this software will often prevent malware from trying to install. <https://www.obdev.at/products/littlesnitch/index.html>
3. Download and install MacScan. You run this manually from time to time to check for issues. <https://www.securemac.com/macscan>
4. Download and install ClamXav for Mac. This is an antiviral. It used to be free, but now there is a fee. <https://www.clamxav.com>
5. Subscribe to MacWorld‘s online newsletter or some other Mac site that will send you emails alerting you to malware issues for Macs.
You don’t have to have all three applications. Check them out and decide for yourself which you feel good about.
Currently the most likely and common way for a Mac to get infected with any malware is by the user helping. That is phishing attacks where some hacker (kindest word I could use) tries to trick you into installing software or entering passwords and or account numbers.
I am vigilant, but I don’t lose sleep over this issue.
*Note: Little Snitch can and will drive you crazy if you just install it. Little Snitch checks all incoming and all outgoing internet connections and asks you if it is OK to allow. It really opens your eyes to see the huge amount of connections that are being made even when you aren’t doing anything and you think your Mac isn’t either. It scares the heck out of most people at first. Read the docs first. Then run Little Snitch in silent mode for awhile. In this mode it will check, but won’t bug you about it. Later you can go and set permissions based on what Little Snitch has collected. Even if you never do this, just the fact that Little Snitch is installed prevents much malware from installing. Apparently the hackers check to see if Little Snitch is installed. If so they skip installing and move on to lower hanging fruit.
I have been using the above software for years and have never found anything on my Macs except for some tracking cookies, which are not usually really malware.
WARNING: Whatever you do, do NOT install MacKeeper. It is bad news and pretty much a scam and difficult to delete. DO NOT INSTALL, EVER!