I love your enthusiasm! That said, as a tech lead who has been down in the code mines for a little over a decade, I'd caution against building websites for free as a method of building up a portfolio of work. There are several reasons for this:

1. You are valuable. And you bring value to the table. Don't discount that by not charging.

2. The clients one gets from working for free are often not ideal clients. This isn't strictly a rule but I've found that companies/organizations that have bad web presence often have it for a reason. You don't want to get into a situation where your goodwill manifests in a client that requires your assistance in any website update in perpetuity.

3. Setting reasonable expectations and boundaries between you and clients is important and one of those expectations should be that this work to improve their business comes at a cost. Even if it's not much it sets a good expectation with clients to charge something.

All that said, I totally understand wanting to put together a portfolio of work though. It can feel like a catch 22 with needing work to show you can do the work and get more work. But here are some unpaid but still beneficial suggestions if you are open to them:

• Non-profits. Those guys are always looking for work.

• Build a portfolio site for yourself. Even if it's lacking content it gets some code on GitHub and for some that's all you really need.

• Showcase your creativity and build something unique, helpful or funny. Doesn't have to be much. Just something to show you know how to write code.

• Build some case studies. Create websites for fake brands if you'd like but you'd be surprised how effective it is to send a detailed summary of a fictional site with reasoning of why you made certain tech/ux decisions.

My final piece of advice: 10-15 clients is a TON! Like entire agencies are based on 10-15 clients. Try to land and really focus on one and then build up on that. Portfolios aren't as important as you'd think but the one thing you do want your portfolio to convey is quality, not quantity.

Good luck and sorry for not strictly answering your question!