Do you draw on paper or digitally?
The short answer is both! Although I use Procreate on my iPad for my digital drawings, nothing beats traditional pencil on paper. Depending on the look I want to achieve, I either scan my original sketches in and clean-up in Adobe Illustrator, or refine my sketches on paper first, then vectorise in Adobe Illustrator. I often use Procreate to create texture and shapes which I then vectorise.
Have a look at my Skillshare class that walks you through how I use Procreate and Illustrator together to achieve an authentic hand drawn look.
Or if you prefer traditional pencil and paper, you might find this class useful.
All my watercolour work is created traditionally (paint and brush on paper), then scanned, cleaned and background removed in Adobe Photoshop.