Even if you can afford to buy a whole case or more for each wine you want to "age", and every year or so, open a bottle and taste it, it is very difficult to assess whether a wine is age worthy and when to drink it. I would say that four are the main elements to keep into consideration when purchasing a age worthy wine. The producer, the vintage, even if good producer in bad vintages do not make the wine and vintage charts do not exist for all regions, the wine itself (eg Barolo is made to be aged) and the grape/wine making process.
The producer, looking at their history and production, we immediately know whether their wines are made to be aged or not. The vintage, this is not just valid for the biggest wine regions, Bordeaux, Barolo, but there are plenty of great, age worthy wine from other regions for which there is no vintage chart, in this case we need to learn more about the producer. The wine itself, by simply entering the wine on google we learn about the wine, how it is made and whether it is made to age or not, lastly the grape/wine making process. There are grapes that are most suited to ageing then others, merlot for example won’t age unless barrel aged, cabernet sauvignon or nebbiolo on the other side are suited to ageing and by knowing the grape and whether the wine maker has used barrels in the wine making process, we will know whether the wine is age worthy or not, but remember, it is just a guess. If you want to learn more read this post