contrast
It will be all washed out if you just take a picture. What you will need to do is, get into the menu of the television set.
Go to "contast" and turn the contrast all the way down. The image will be a lot darker than before. Turn off all the lights in the room. Now, take the picture.
That is the best way to get the best iamge taking a picture from a screen. If you ever shoot a video, of a girl being tickled, and you want her to watch television, do that and you will actually be able to see what she is watching rather than see a washed out really bright TV image in the background.
However, these days, video capture cards, anaolg especially, are really cheap. Below $100. That will be a whole new frontier, and obviously will generate a much better image. I think you might want to look into those.
Good luck.