Natural and DIY Skincare and Chemicals: You Ask, I Answer

Here's my second "You Ask, I Answer" post, where I consolidate some common (and not so common) reader questions. Reader questions aren't a new thing on my blog, and I've written a bunch of posts based on reader questions over time, including some of my personal favourite science-y posts, like my post on parabens, and my post on talc. But I thought it would be nice if I could share some of my reader Q&As with everyone else too!

Today's question on DIY and natural skincare comes from Chelsi:

Chelsi asks:
I want to ask u something. It's so hard for me to get organic and natural skincare that avoids not using harmful chemicals...the fact is there are lots of brands outside there use chemical ingredients... I want to make DIY skincare but I think i don't have enough time to make it while I have to work and after work I am tired and just wanna take a rest..So , do you think it's okay to still using the skincare which still contains chemical ingredients? thx :)

Your question is quite a big hairy one, so I'll just touch on some key topics that you raised:
1. Are chemicals really a problem in skincare?
2. So when should I avoid "chemical" ingredients?
3. Can you actually DIY your own skincare, and if so, is it actually "better" that what's available out there?