At least for me, instead of learning a bunch of disparate things separately, it's much more motivating to put things in a larger context and actually build something tangible out of it.
And by product I don't necessarily mean something you can earn tons of money from. Of course it's nice if your product can make you a gazillion dollars, but it's ok too to make a product that noone wants to pay a dime for. (I'm from a socialist country!) As long as you are having fun and learning something during the process, it's all good. I believe all learning has value, strengthening you and increasing your chances of favorable positions down the road.
To create a product means to identify a chain of sub-problems that needs to be solved, deciding on an order in which to solve them, and then solving them one by one. Some sub-problems may require you to look things up and learn (it's ok to use Wikipedia!), and some sub-problems are things you need to invent, or just execute. Some of the sub-problems are obvious when you think of the product in the first place, but I believe most products also have a bunch of hidden sub-problems. Problems that you don't come across or imagine unless you actually start breaking things down and get working on making the product. Stumbling upon and solving those problems are valuable too, sometimes more so than working on the most obvious ones.
Besides from learning many new things from solving these sub-problems, creating a product is a nice feeling. You can show a product to others as a tangible demonstration of your skills and creativity. Perhaps you can even sell the product and earn money from it. Or if not, perhaps it spawns ideas for new products that will. (Then go make those!)
So how do you start? Which product will you make? Perhaps you don't have a killer idea for a completely new revolutionary product that will rock the world. It's ok. I know a fun exercise: Think of an existing product and try to figure out how it's made. Which problems need to be solved to make product X? What do you need to learn, and which things do you have to create, and in which order? As a next step, how about seeing if you actually can make it? Perhaps you're not able to set off enough time to create say a next-gen particle accelerator, but hey if you look around there are tons of smaller products that could be fun to emulate and learn from. Be kind to yourself and let the definition of product encompass things that can be made in one or a few hours.
So, try to come up with a product. Or steal one.
Eventually when you're finished making the product, write about it. As they say, "learning by teaching" is perhaps the best way of learning. By figuring out how to teach something in a clear way to someone else, you force yourself to organize your thoughts. You think about which are the important parts and which parts can be left out. You think about in which order to present all the sub-problems. You imagine questions, forcing you to really think things through and not brushing over any important details. Also it gives you valuable writing practice.
And once you're finished writing, you know what? You just got yourself another product. Because your writing is most definitely a product too. Hey, now you have two!
1. Think of a problem or something you want to learn
2. Make a product out of it
3. Write about it
Simple, isn't it?
A particle accelerator. You know, for inspiration. No pressure!