This is Zach Weiner(Author of SMBC)'s AMA, someone asked about his creative process, here's his response:

Ideally, I spend the first 5-8 hours of my day learning science/math, then 3-4 hours writing jokes, then 2-4 hours reading a book, then at the end of the day I draw.

So yeah. Basically, the main thing is to get a lot of good input if you wanna have a lot of good output. Writer's block is bullshit. If you're putting in the time to intake info, process it, and sit at your keyboard fighting for good ideas, you'll never hit a wall.