Most rooms will have painted walls, if you see marks paint, however, remember that when you paint a small area this will look out of place to the rest of the room. My suggestion is to paint a wall if there are multiple marks as you will then not see patches everywhere.
Use vinyl matt emulsion, don’t buy the cheapest paint from a DIY store, use a good quality paint like Dulux or Leyland, don’t use a trade paint as this is watery and you will end up having to give the walls many coats.
When it comes to woodwork this can look stained and colour fades over time, before you attempt to paint this as many are gloss or eggshell, use sugar soap, this will take all grime and stains off which will eliminate the need to use a paint.
If this is not the case then use this guide to painting walls and woodwork