His artistic education was largely self-directed, with brief formal training under lithographer John H. Bufford and painter Frédéric Rondel. Homer's mature style evolved through distinct phases: early genre scenes of rural life and childhood, Civil War documentation, idyllic depictions of American leisure, and finally his powerful marine paintings created during his seclusion at Prouts Neck, Maine.

His signature authentication is remarkably consistent throughout his career, typically appearing as "Homer" in cursive script, often with the date. The signature exhibits distinctive characteristics: the "H" features an elaborate looped ascender, the "o" is open and rounded, the "m" shows consistent humps, the "e" is clearly formed, and the "r" concludes with a distinctive flourish.

Homer frequently signed in the lower right corner of paintings, though early works may show variations in placement. Authentication markers include the fluid, confident stroke quality of an experienced artist, consistent letter proportions, and the characteristic dot over the "i" often rendered as a small circle rather than a simple dot.

Period-specific variations exist: early signatures (pre-1870) may show more tentative execution, mature period signatures (1870-1900) display confident fluidity, and late works (post-1900) maintain consistency with slight variations in pressure. Authentic signatures should show proper aging consistent with the painting's medium and varnish, with no signs of modern pigments or inconsistent craquelure.