'Airsoft flashlight'
When asked for purchasing advice by friends, family or colleagues, especially those of whom are novices in said hobby or field, I always give the following warning: When shopping online, be careful not to restrict your searches by adding arbitrary keywords specifying your use case, when the item has a more general purpose.
I coined the term 'airsoft flashlight' after being approached by a friend who was lamenting his difficulty finding a high quality flashlight for use during his airsoft matches. After asking how he was searching for one, he explained he had simply searched for 'airsoft flashlghts'. I asked him what differentiated a generic flashlight from an 'airsoft flashlight', and was met with reticent pause.
This advice can also extend to general web search queries (especially in light of how dismal Google search has become). For instance, instad of searching "Synology NAS compatibility Seagate ST22000NT001 22TB HDD", I might instead broaden my search to "Synology NAS compatibility 22TB HDD".
This may be obvious for some, but I find myself forgetting this trick when shopping for, or troubleshooting very specific things.