You can paint it on the hinges be sure to cover them in painters tape but laying it flat will help prevents drips and runs.
Front door hinges paint.
Instructions clean and prep the door.
Depending on the condition of any old.
Just as with the primer let each side of the door dry before turning it over to work on the other side.
Give a light sanding to the entire door to give the paint a rough surface to grip.
You can paint your door in place or remove it from the hinges if you have a storm or glass door to protect your home and keep bugs and debris from floating into your home.
Add at least two coats of paint to the door using three or more if you want to increase the color saturation.
Make long strokes with the brush and clean any visible lines on the front of the door with a dry cloth.
If you have the patience space and materials go ahead and take your door off the hinges and lay it flat on sawhorse legs.
You can also tape a tarp over the opening if you prefer to remove your door to paint.
Sandpaper fine grit damp rag paint brush low nap or foam roller and roller tray screwdriver to remover door hardware quart of paint quart of primer somewhat optional explained below ready strip safer paint and varnish remover optional based on the condition of your door hard.
Wipe down the door to remove all the girt and grime.