If you are familiar with photoshop I can give you a few tips (I've used it for pixel art for years)
First go into every tool (eraser, selection, fill, etc) and make sure every anti-alias option is disabled. For the eraser change the mode from "brush" to "pencil"
Go into Properties (ctrl+K) > General and set Image Interpolation to Nearest Neighbor. In Units and Rulers change both units to Pixel
Go into Window > Arrange > New Window for (file name). Set it to the side at 2x zoom as a preview for your main window, which you usually zoom in a lot closer