A heat pump runs in both directions, so it asks for attention in both seasons. The habits below are the ones that keep it doing its job over the years. None of them are repairs. They are the checks an owner can make without tools.
Keep the outdoor unit clear
Walk around the outdoor unit each season. Snow, leaves, grass clippings, and stored items should not sit against its sides or block the top. In winter, clear the snow back from the unit so that air can reach the coil on all sides. Keep the area around it open enough that you could reach the service panel without moving anything heavy.
Read the defrost cycle as normal
In cold weather, the outdoor coil can frost, and the unit runs a short defrost cycle to clear it. During that cycle you may see steam or vapor coming off the outdoor unit and the air from the indoor unit may feel cooler for a few minutes. That is the cycle doing its work. Note how often it runs and how long it lasts in your own house. A change in that pattern over time is worth writing down and raising with the installer, and it is more useful as a log than as a worry.
Thermostat and the emergency heat setting
Ask your installer to show you the emergency or auxiliary heat setting and to explain when it engages on its own. Many owners leave the thermostat on automatic and never look at it again. Check it at the start of each cold season. Use the emergency setting by hand only when the installer has told you to, and turn it back to the normal heat pump mode once the reason has passed.
The indoor side and the filter
Check the filter on the indoor unit on the schedule the installer gave you, and replace it when it is dirty. A clogged filter cuts the air moving across the coil and makes the whole system work harder. Look at the indoor drain line as well, and make sure it is not holding water or leaking.
Keep a short log
A simple record is enough. Write down the install date, the date of each seasonal check, any change in the defrost pattern, and any time the emergency setting was used by hand. That record does two jobs. It helps a technician see what has been happening, and it gives you a clear picture when you plan ahead. The Heat Pump page on this site explains typical service life and how to turn an install year into a planning date.