I know that using Linux is the fastest way to learn it, but what are some things I can try to do to build up those skills?
Slow down there, buckaroo. Not to talk shit about jumping from OSX to Linux, but you're moving from one Unix-like substrate over to another, and not necessarily taking advantage of what you
already have access to. There's also the matter of some
very obscure situations where you'd
need a Windows or Mac computer (i.e. me being a retard who uses an iPhone and needs a place to backup, sync, etc).
If you wanna get your feet wet with Unix-like stuff without going full-on balls to the wall purge everything on my MacBook and take the plunge into Linux Land... just install some basic FOSS programs through
MacPorts. Make sure you open up the Mac terminal, and key in
xcode-select --install then hit "Enter" so that you're able to properly bootstrap MacPorts.
Without getting too lost in the weeds of what it is: MacPorts, Fink, and Homebrew are all "package managers" for OSX. In the before times, most software made for one Unix environment could be "ported" over to another. That meant (and still kinda but not always does) Linux and Mac had
tons of overlap in FOSS programs that one could run on their machine. This is about as close to the Linux experience as you can reasonably get without purging your drive and suffering from Linux remorse like 3-4 months down the line when that obscure use case for OSX rears its head..