Ask HN: How to handle tasks that require design skills as a freelance web dev?

I like to believe that I have a good taste for design, but lack of experience, and overall poor "design vocabulary" wouldn't allow me to make such things efficiently.

As my clients are usually small businesses, they don't have a designer nor willing to find one. They feel comfortable with having a single guy handling everything. And that's understandable in such market. But I have no idea how much should charge for the way-beyond-secondary skillset.

Sometimes I try to explain, that I'm not exactly the right guy for the job when it comes to "drawing". The common argument is: "it doesn't really matter as long as you can deliver something that works".

I love to make my clients happy, so I don't turn them down immediately. Maybe they really are in need of just something in order to function properly. So I try hard to make the thing.

Results aren't exactly awful, and clients seem to be happy. Sometimes I even like the end-result myself. But at least half of the time it doesn't look good enough to me.

I never had a complaint, but I feel bad charging the same amount I ask for my primary skillset. And the time spent is just ridiculous compared to the other things I do!

For example, I can make a markup and implement backend in, say, 2 hours. And then, there would be 5 to 8 hours that are spent tinkering with fonts, images, colors, spacings.

How should I charge? Should I avoid such feats? Should I hire a designer? Or maybe I should develop needed skills myself as I am kinda already stepped into it?

It's also worth noting that I never have never hired a freelance designer, so it's a bit frightening.

Please, tell me about your experience.