Oesten's etudes often feature accessible melodies and straightforward accompaniments, designed to develop graceful playing.
Practice evenness in the right-hand melodic line and ensure a clear, supportive accompaniment.
2 Melodien (Op.45) is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 4.
You should be comfortable at Henle level 4 — meaning you can already play level 3–4 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of 2 Melodien (Op.45) lasts about 3.5 minutes.
2 Melodien (Op.45) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.