You might also want to keep all of your receipts in case you do end up in court. The golden rule to remember is to not make any improvements the landlord doesn't want, especially if you ever want to see your security deposit again. However, your landlord might like your improvement idea. If your landlord thinks your work will enhance the apartment, you could try to get some financial support for it. Perhaps your landlord will foot the bill or at least buy some paint.
Some landlords prefer to do the work themselves to ensure that it is done to their high standards.
In this case, you might pay for the paint or supplies, and the landlord might cover the labor costs. Well, perhaps it's time to apply your passion to something that won't get you evicted, like woodworking or Feng Shui classes at your local Adult school.