General Resources:

The first place I go to learn about a new technology or skill is Reddit. So many different things have a specific Subreddit that includes a community driven wiki. This wiki generally contains learning resources, active communities for support and many more things specific to that technology. From there, choose resources that fit your learning style and get involved!

CompTIA Certifications:

I would highly recommend checking out Professor Messer on YouTube. He produces high quality, up to date and very comprehensive video courses on the A+, Network+ and Security+ certifications. On top of that, he also created an awesome set of course notes and practice exams that he offers for sale on his website. I found these practice exams to be crucial in my success passing the A+ core 1 exam.