The easiest way? Why must there always be an easy way to truly learn something well, developing some real expertise at it? Have you heard the old rule about 10,000 hours? No, I am not going to suggest that to do anything at all using MATLAB, you must be a true master of it. But the more time spent at a task, the better will you be. You need to learn to think as a programmer.
The easy way is just time invested. Make mistakes, try a different approach. Write code, then rewrite it in a better way. ( I recall one significant piece of code I wrote 7 times. Each time it improved, becoming faster, more efficient, more user friendly, more capable with each instance of course.) And now that I think of it, I've since written two more versions.
Read the forums, here, and other places. I still learn new things on Answers, after having used MATLAB for longer than many of the people who will read my answer have been alive.
A personal favorite of mine is to solve problems, using MATLAB to solve interesting problems that push my own limits. For this, perhaps the best are the Project Euler problems, with now many hundreds of them listed. (I ran out of steam after solving over 300 of them, so if you do better than that you have arrived. :) At least the first few are pretty easy, but as you go more deeply, you will learn much. You can also learn a lot of mathematics from them, as well as computing skills you never knew existed.
A (generally) slightly easier source of problems are the Cody problems, found right here on MATLAB Central. These can form a great test of your skills as you improve, though I have often observed that to write the best scoring solution often involves using various hacks that are not relevant to good programming skills. So try to avoid the hacks.
Just keep on pushing yourself, using MATLAB. Don't give up. And before you know it, you will see your skills improving.
