Having curly hair makes it more difficult to color your hair. But that does not mean that you cannot color your hair at all. You just need to catch hold of a hair stylist who will know how to deal with curly hair. He should understand how your curls will react and absorb the color. If your hair is extremely fragile, then you need to avoid any hair color that has bleach in it.
If you have very difficult curly hair, then it is better to go to a salon instead of trying to color your hair at home. If you find it difficult to color your hair frequently, then you must explain this to your hair expert and ask him to suggest a color program that will need minimum maintenance. Avoid visiting a colorist who is only interested in doing foils and will not do free form hair painting.
Coloring shampoos are recommended for maintaining your colored tresses. But you need to keep in mind that they can dry your hair to a great extent. It will do you good if you do not shampoo your hair for at least three days after coloring. This will not only help your color to settle down but also helps your curls recover from stress.