If you prefer to learn in a more structured/classroom environment, I would recommend the training courses from MathWorks:
- MATLAB Fundamentals
- MATLAB-Based Optimization Techniques
- Parallel Computing with MATLAB
- Statistical Methods in MATLAB
- MATLAB For Data Processing and Visualization
- MATLAB For Building Graphical User Interfaces
- MATLAB Programming Techniques
Obviously, pick the ones that apply to what you want to do.
There are also some (free) interactive tutorials available on the MathWorks web site.