When it comes to designing digital artwork for print, there are all types of software available. The best practices listed below will work in theory for any software, but the step-by-step instructions will only be relevant for Photoshop users.
There are two types of graphics when it comes to print; raster and vector. Raster artworks are constructed of pixels to form an image and are typically made and edited in tools like Photoshop. Printers, phones, and other display devices are all raster-based devices. Vector artworks are a little more complicated but are files that essentially can be scaled to any size without a drop in quality.
Both types have their limitations, so it's best to know the kind of artwork you want to make before deciding which software to use and how you want to print.
Traditional artists naturally gravitate to photoshop because its tools and digital brushes translate well from real-world drawing and painting. Illustrator is widely used by graphic designers to make clear, precise shapes and designs with a keyboard and mouse.