Personally, I think your skills should be like a liberal arts educations where you touch on a little of everything. So here is a list of skills I think you should be able to highlight in your portfolio and be able to speak to them in an interview.
Here a few tips to help you get started:
If you want to stay in this industry and keep up with your skills, then having a portfolio is critical. You can’t always control your circumstances, but you can control how you prepare for them.
source : http://www.articulate.com/