Your first Palette House project should reduce guessing. Choose a design with a clear pattern sheet, a small number of colors, and a shape you can recognize even before the details are added.
Good first projects include food icons, signs, books, small props, simple clothing motifs, terrain tiles, bows, stripes, collars, and other flat shapes. These teach the basic rhythm of counting squares, filling blocks, and checking alignment.
Avoid detailed faces, anime portraits, realistic shading, complex pets, and house exteriors copied only from angled 3D screenshots. Those are not impossible, but they require more judgment than a new player usually has on day one.