What is the easiest way to make some Cash?

I have just bought a flat and realise that I am now going to be skint for the next 25 years. I have to furnish the flat and also have a life if possible. Any suggestions for ways of making money. I am highly intelligenta dn creatibe and can turn my hand to most things, I do have a full time job but am happy to work weekends and evenings, and particularly interested in things I can do from home!