Become a SysAdmin
Here are the things that you need to study in order to become a succssfully System Administrator and end up with a high paying job
Programming basics
Everyone should have some basic programming knowledge. You can choose any programming language, it does not really matter. You just need to make sure that you are familiar with the basics. You can start with Python, Java, PHP or any other language. My personal favorite is PHP. Here's a link to a cool guide that you could go though
PHP 7
Linux
Get some administration experience in Linux. Develop a good working knowledge of Linux using both the graphical interface and command line, covering the major Linux distribution families.
I recommend this free Introduction to Linux course from the The Linux foundation!
Don't forget to deploy a few virtual machines and practice what you've learned, use this link to get 50$ free credit: Digital Ocean
Linux
Networking
Learn the basics like the OSI model, clients and servers, protocols, IP addresses, network hubs, switches and cables, routers and firewalls.
For very beginners I would recommend this course on Udemy here:
Networking
Windows
You should at least have some basic understanding and know how to manage windows servers as well. I would recommend going though this free Windows Server Administration Fundamentals.
I would also suggest playing around with IIS and MSSQL a bit.
Windows
BASH Scripting
As a good sysadmin you should know how to read and write BASH scripts in order to automate your daily tasks and speed up your deployment process.
Checkout this great course on the Linux Academy website where you would be introduced to the power of BASH!
Linux Academy
Keep exploring
Once you've mastered the basics of Linux, Networking, Windows, Virtualization and Scripting you should stay motivated and keep learning new things like:
Virtualization - VMware
Containers - Docker
Container Orchestration - Kubernetes
Cloud Providers - AWS
CI/CD
And more..
Linux Academy