i was doing pages at 940x1410px and then 1200x1800(?) and THEN i realized that those were too small to print. trust me - if you ever want to print, or even if you don't, consider using at LEAST standard comic book sizes. there are good templates on sites like kablam, and if you get clip studio paint, it has a super easy way to add the guides for margins/trim/etc
now i use 2100x3150(7x10.5 in) at 300dpi. i've heard that 600dpi is better for black and white but i work in color so i use the lower resolution
(unfortunately i have to go back and redo the first 30~ pages of my comic because of how uninformed i was about page sizes prior to starting my project)