Use ISP Provided Tech
This has to be one of the biggest ones. Hear me now. ISP provided equipment is almost always trash or a gimmick. It’s okay to use their modem in cases you have to (IE Fiber), but ALWAYS use your own router.
Use a Low End Router
Always go with the best you can afford. Generally I’d recommend staying away from most consumer grade products that are filled with bloat or lack some more advanced features. IE: Eero/Google Wifi/Most mesh systems (too few ethernet ports, no web interface) and mostly everything you can buy at Best Buy or Costco. I say stick with the brands like Mikrotik, Ubiquiti and TP-Link.
Use the default anything
Don’t use the default SSID (wifi names, IE: Netgear232, Centurylink8272). Definitely change that default wifi and admin password as well.
Having speeds below 50mbps
By modern day standards, this should be the minimum speed you have. Then, the more devices you have spread this number thin. While it’s more complex than that, general rule of thumb is always go for as much speed as you can afford if you’re at all active on the internet and/or have many devices. Find that sweet spot for your usage.
Expecting full speed on wifi
Wifi is full of distractions for your tech. While it’s fine for streaming and general usage, if using it for business or gaming, best to hardwire.