das Glück des Tüchtigen — The luck of the capable. DWDS: the success that an active, determined person fights for. One sports report used it for a late goal by a player who had worked hard all game. Wikiquote gives a line by Field Marshal Helmuth von Moltke from his essay Über Strategie in shortened form: Glück hat auf Dauer […] nur der Tüchtige. In the long run, only the capable man has luck.
mehr Glück als Verstand haben — To have more luck than sense. DWDS: said of a lucky person.
Ein blindes Huhn findet auch mal ein Korn. — Even a blind hen finds a grain now and then. DWDS: even the least capable person sometimes succeeds.
auf gut Glück — On good luck. DWDS: without any guarantee of a good result.