How to design a circuit
I would say design as much as you can. I liked electrical engineering as a hobby. While I was in school I would also design PCB's and have a few projects on the side in my spare time. I did this to start a company, none of the projects ever got to that level, but I gained some valuable skills that made it easy for me to get a great job.

Another way I gained skills is through student projects. I did the equivalent of 5 projects that would have qualified for a senior design project. 

You need to start looking at job postings, and look at the jobs you'd want to have and then look at the requirements. Then come up with a project that you need to learn X skill or X tool. Your employers will thank you for having those skills. 

If you want a DSP job, then buy a DSP board and start working through tutorials, if you want an analog engineering job then build your own op-amp out of discreets. There is sooo soo much information out there, there are videos and tutorials on many things. 


Learn what resources you need
Learn how to find the resource and interpolate between different resources
(do I need a book? a web tutorial\resource? a research paper?)
Build your thing.