Before you wash the wall, it is better to clean it from dust by duster or vacuum cleaner.
Clean the dirtiest parts, such as finger prints, crayons or other stains with steel wood pad soaked into soap water. Be careful not to scratch the wall.
Use corn flour and paper towel to absorb the grease which stains your wall. Wipe it until clean after the grease had been absorbed.
When you clean the wall, start from the bottom, then move to the top. Use all-purpose cleaner made from:
1. One cup of ammonia (handle with care).
2. A half cup of vinegar.
3. A quarter cup of baking soda.
4. Four liters of water.
To remind you the cleaning starting point, start from one corner. The starting point shall not be wider than one meter square. After you finish, move to the next one meter until the whole room had been covered.
If you do not have a stepladder, use sponge with handle to reach difficult parts. To prevent making the floor wet, cover the floor with newspaper or cloth prior cleaning the wall.