One should handle Stardust carefully in Pokémon GO.
Perhaps you have already experienced the situation where you wanted to pump your favorite Pokémon full of tons of Stardust to make your companion even stronger. However, you should exercise caution and patience, as Stardust is valuable.
Farming Stardust in Pokémon GO
Farming Stardust is not that easy, as you currently only receive it by catching wild Pokémon, claiming Arena rewards, and hatching eggs. So if you catch a lot of wild Pokémon, you can slowly but surely accumulate a certain stock of Stardust, which you should only spend wisely.
In our tips on how to quickly and effectively increase your trainer level, we already outlined the advantages of catching frequently occurring Pokémon. If you do this regularly, you will receive even more Stardust on top.
Improving the right Pokémon with Stardust
When you give a Pokémon Stardust, you increase, among other things, its CP value. The higher this value is, the stronger your Pokémon becomes. However, it is most worthwhile to supply a Pokémon that already has a high CP value with Stardust, so that this value gets even higher. Providing a Pidgey with 144 CP with Stardust is not particularly good, as you will find wild Pidgeys with a base CP higher than 144 with a higher trainer level.
If you catch a Pokémon at a higher trainer level whose base CP is already significantly higher than what you usually see in wild Pokémon, then upgrading with Stardust is worthwhile. If the Pokémon also has strong attacks, your chances of success in gym battles are further increased. Here you can see which are the best attacks of Pokémon in Pokémon GO.
In summary: Upgrades with Stardust only make sense and are effective when you have reached a high trainer level (Lvl 10 or higher). Because at higher trainer levels, you automatically find Pokémon with high CP. At the later levels, you need more experience points for a level-up, which makes the CP values of wild Pokémon more consistent.
In our Pokémon GO guide collection you can find more tips and tricks for aspiring trainers.

