With a septic you have to be a bit careful what you put down the drain as you dont want to kill or overwhelm the bacteria living in it that break down the poo etc.
Dont use lots of bleach and chemicals all at once
Dont put lots of oils or fats down
Dont put tonnes of water down at the same time (if someone is showering dont run the dishwasher, washing machine and flush all the loos at the same time!)
NEVER put stuff in that wont biodegrade (earbuds, panty liners, wet wipes)
You can get an additive to chuck down that encourages good bacteria if you want to be extra careful
Technically if your leach field is working well you shouldn’t need to pump it, but most people do anyway as its difficult to know if your leach field isnt working until it doesnt…and that is a big problem.
You should get it inspected before you buy to make sure its in good working order as the pipes can get crush/cracked/break down over time and also that it is sized correctly for the house/number of bathrooms
Septics are really expensive to install/replace, so if it is close to the end of life get several quotes on replacing it before buying the house
Oh and the last thing is dont drive over it (tanks and field) with anything heavy (lawnmower is fine) and dont grown anything bigger than a small bush over it or the roots might get into it. So if its located in a silly place, it might make it difficult to renovate or access your garden with a digger etc