Setup inkscape

import the inkscape palette in the Tools folder. how?:
copy other/aleta-postre.gpl to your inkscape folder. In gnu linux are two possibilities: if you have the flatpak version: ~/.var/app/org.inkscape.Inkscape/config/inkscape/palettes if you have the native version: ~/.config/inkscape/palettes.

Concepts

here is an image describing the parts of an icon of aleta.

there is two designs in aleta. Lined and Filled. Filled is preferred over lined.

here is the two designs over the same icon:

the position of the foreground will fit in the hints.
the foreground must be white. This don't mean that you will draw every path in white. you can use any color you want while drawing. this means that the result of your drawing session is an icon with a white foreground
the minimal width is a square of the grid. preferably make «2 squares lines» as minimum.
if the icon is too complex, try to simplify it.
please use the original color¹; if the original icon shows many colors, decide by yourself what are the best color to use.
you can use plain colors, but gradients are appreciated.

¹: in aleta postre, i have changed the color rules and now aleta uses the original colors of the apps. there is no more the needing of a palette.