Firstly, it is recommended not only to let the old oil drain completely, but also to rotate the engine crankshaft 5-7 revolutions to remove the remaining oil from the oil lines. It is also useful to flush the engine (for this purpose, a special washing oil is used) for 20-25 minutes, while the engine should be idling.
When changing the oil, always change the filter as well. Old, albeit washed, will be «like a fly in the ointment in a barrel of honey».
Oil should be changed indoors, where there is no dust and wind.
When checking the oil level in the crankcase, the cloth used to wipe the dipstick must be clean. Even seemingly insignificant dust particles that get into the engine significantly reduce its service life.
When changing the oil, they also change the gasket of the drain plug in the engine oil pan, as well as the oil filter housing (if it is installed). The gasket is included with the oil filter.
After changing the oil, it is useful to record the mileage of the car, the date of replacement, the brand of oil, so that there will be less problems during its subsequent replacement or topping up.
You should not be afraid that the oil will darken after 1000 km of run. This only indicates that it «works» right - it retains carbon deposits and washes the surfaces of parts.