answer:Do a functional resume, which sections by skill rather than by job, and you can list the things you’ve done in each section which have contributed to and prove your mastery of the skill in question. I’ve seen a couple of studies which show that where you got a given skill is less important to employers than actually possessing it, so volunteer work and life experience are perfectly valid to list in your functional resume. If you need tips on writing a functional resume, I recommend Yana Parker’s Damn Good Resume Guide.