The first thing I would make sure of is that it comes from one of the four major regions. These regions are the Mosel, Pheinhessen, Rheigau, and Pfalz, which, in my opinion, are the most important quality wine-producing regions in all of Germany.
Next, look to see if the wine is made from the Riesling grape. Anyone who studies and enjoys German wines finds that Riesling shows the best-tasting characteristics. Riesling on the label is a mark of quality.
Also, be aware of the vintage. It’s important, especially with German wines, to know if the wine was made in a good year.
Finally, the most important consideration is to buy from a reputable grower or producer.