Sowiński's melodic etudes aim to develop technical fluency within melodically driven contexts. These pieces often require nimble fingers and a clear musical line.
Focus on developing rapid, even articulation in scales and arpeggios while maintaining a clear melodic contour.
12 Études mélodiques (Op.124) is rated Henle level 3 of 9 — late beginner repertoire, roughly ABRSM grades 4–5.
You should be comfortable at Henle level 3 — meaning you can already play level 2–3 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
12 Études mélodiques (Op.124) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.