Colour chips and paint samples exist to save you from getting it really wrong. It may seem extravagant to spend the time and money on renting a fan deck or buying a real sample of paint, but I prefer to think of it as purchasing an insurance policy on your colour. It could save you the time and expense of re-painting the room when you discover half way through that the gentle shade of green you have chosen are making those tiles you can't change look an awful shade of pink!
Once you have some ideas about the direction you want to go, start the testing process by collecting a variety of colour chips in that ball park. It's important to see the colours in the correct context, so hold them next to those elements which will be staying in the space. Once you've narrowed it down to 2 or 3 options, it's never a bad idea to try sample right on your wall!