Clear away any obstacles for Wi-Fi, and leave your router out in the open! Hygiene and keeping a tidy house are important, but Wi-Fi signals need a clear line of sight to work well:
You can read more about this here: Stop clearing away your Wi-Fi signal
Always use the latest firmware -- make sure you have all system updates and drivers for:
Especially for older computers, smartphones, and gadgets, this can be crucial to working well with newer network equipment.
If you have a Windows computer with a wireless adapter from Intel, you should install Intel's own driver update application, as several of their most important updates have not been included in collective Windows updates. You can read more about this here (the Intel issues are not exclusive to Wi-Fi 6): Wifi 6: Compatibility issues you should know about.
Do you have Wi-Fi problems with a specific computer or device? Take a look at Checklist when you can't connect to Wi-Fi (or get thrown off)
If you have a desktop computer, gaming console or other equipment near the router and/or network outlet, connect it by Ethernet cable provided you have one available.
Wired internet access will always be more stable than wireless, and each device using a cable is one less fighting over wireless capacity.