To learn to understand any complex topic or skill you first have to adopt the mindset necessary for learning. Most people I come across seem oblivious to this and have concluded that their potential for learning is very limited. Nobody ever told these people what the actual potential for learning is and why attitude towards learning is the real determining factor.
Over the course of my life learning different skills towards mastery I got increasingly aware the farther I got of how my own cognition works as it applies to learning and how I can regulate that process over time and apply it to things that might not be directly apparent at first glance to learn more easily. Then one day in my mid 20's I found out there's a word for the way I've grown to think about learning: Metacognition.
Learning something new and unfamiliar can take a lot of time, so don't give up. Just be mindful of the fact it's okay for things to take a long time. It took me years to learn enough to compile the things that are contained in this book. But hopefully you the reader can learn these things faster with my help so you won't have to put in as much time.
Adopt a positive mindset about your own learning potential. Persistence is the most important thing. Okay to fail but try again don't fail forever. If you start slow is fine as long as you're intending to continue making attempts, and do it long enough and you might do it more.
You have to take responsibility for your own learning, ultimately over time you're the one who's shaping your own brain. The brain is like a muscle. Most people have a misconception about learning but the truth is a vast majority can learn almost anything if putting in the time, sure it takes time but if you embrace learning, it will only get easier and more effortless to learn new things over time. If you do the opposite, actively avoid learning new things and start associating it with unpleasant feelings then learning new things will just get harder and harder. Just let go of not understanding something right away, just keep trying and remember you will get it with time.
Learn through project goals.
Big goals, and subgoals.
Read research papers in topics of interest.
If you don't understand something, read it multiple times. If you still don't understand try finding another explanation online or from other books. This is what I did. It will get easier to understand new concepts right away the farther you get into math.
Look if a local technical college or university offers any way of meeting with engineers. Find and join a hackerspace (hackerspaces.org). Try to find people who posses the skills and knowledge you wish you'd have and ask them for help to learn first hand.