Be the done thing
Definition 1 of 1
Pro Tip 1/3Social Norms
Refers to actions that align with societal expectations or etiquette at a certain time. 
Wearing a suit to a job interview is still very much the done thing.
Pro Tip 2/3Time-Sensitive
What may be the done thing today can change and become outdated over time. 
Sending hand-written letters was the done thing before emails became popular.
Pro Tip 3/3Cultural Variance
The done thing can differ between cultures, so it's important to be aware of local customs. 
In Japan, removing your shoes before entering a home is the done thing.