Be very careful to put the right number. The cards can all be kept numerically in a special box. If you have a kit with floss, follow the instructions for organizing the floss carefully. If you wish to wash your floss or fabric, please do it before you sew your cross stitch. If one color runs in the completed project, you will probably never get the discoloration out.
Some people wash their skeins in a mild warm soapy water.
Then rinse until clear. Dark colors are more likely to run, but good quality threads and fabrics should not. Starting Cross Stitch Frames and Hoops Vol. Keep your work as taunt as possible. You will need either a frame or a circular hoop.