Choosing the right colors

I really want to repaint the rooms in my house. There is nothing really wrong with the colors that are already on the walls, they are actually similar to what I would do myself. However, they are not quite what I want. The tan is a little too brown and a little too dark. The green is also too much in the bedroom since the curtains and carpet are about the same color. I need to go get some paint samples from the store so I can see about picking out new, slightly different colors that are more to my liking.