In general, The Comics Journal is a great source for interviews with cartoonists. Here are a few interviews of cartoonists about their work from a variety of sources:
In this article from the Brooklyn Rail, Ebony Flowers, author of Hot Comb, discusses inspirations behind the stories in the book and how her academic background (a PhD in anthropology) influences her perspective.
In this interview from the Los Angeles Review of Books blog, she talks about writing her dissertation mainly in comics, how she moved into making comics from academia, her process, and her next project.
In this Comics Journal interview, Kate Beaton, author of the humorous and historical Hark! A Vagrant! webcomic and other works, talks about how she got started in comics, her process, and the importance of her comics-making community.
In this Lithub.com interview, Jason Lutes, author of the Berlin series, talks about:
* doing visual and reading research to make his between-the-World-Wars Germany convincing;
* what he thinks about drawing parallels between the past and the present political situation; and more.
(more on lithub.com as a website here)
In this Rumpus interview, Phoebe Gloeckner discusses her work in the graphic novels A Child's Life and The Diary of a Teenage Girl. She also speaks of her later art/writing project in Juarez, Mexico.
Content note: please be aware that Gloeckner depicts and discusses sexual violence very frankly.
20 Questions with Cartoonists - a blog that ran from 2008-2010 (author: Austin English) that asked cartoonists these 20 detailed questions about their process:
1. Can you describe your drawing routine---how often you draw, how many hours per day---how you break up the day with drawing?
2. How much revision/editing do you do in your work?
3. Talk about your process---do you write a script or make up the drawing as you go?
4. Do you compose the page as a whole or do you focus more on individual panel composition?
5. What tools do you use (please list all)?
6. What kind(s) of paper do you use?
7. Do you read a lot of comics? Are you someone who reads comics and then gets excited to make more comics---or is your passion for making comics not linked to any particular love for other comics?
8. Do you make comics for a living? If not, how do you support yourself, and how does this relate to your comics making process?
9. Do other art forms often seem more attractive to you?
10. What artwork (or artists) do you feel kinship with?
11. Is a community of artists important or not important to you?
12. Is there a particular line quality you like---thick/thin/clean/etc?
13. What is more important to you---style or idea?
14. Is drawing a pleasure to you or a pain?
15. When you meet someone new, do you talk about being an artist right away? Do you identify yourself as an artist or something else?
16. Do you feel at all connected to older comic artists like Steve Ditko or Jack Kirby---or does this seem like a foreign world to you?
17. Do you ever feel the impulse to not draw comics?
18. Do you draw from life?
19. Do you pencil out comics and then ink? or do you sometimes not pencil?
20. What does your drawing space look like?