After accepting the responsibility and getting familiar with the tasks, there are many thing you may realize need attention.
One of the first and probably most important with those who have dementia would be making sure the house or apartment is secure. “Wandering” is a common trait with such people. My mom did wander out of the house once. To make sure that would not happen again, I had another deadbolt lock installed on the front door which required a key to open from the inside as well as the outside. It would be wise to check with local laws and also to keep a key near the door but hidden from sight in case that exit is required due to an emergency (fire, for example).
Another useful item are assist/safety bars in the shower or bathtub. The photos on this pages show the ones I had. If the person being cared for is on Medicare, it should be available at no charge. Someone even came out to install the bars.