To become a famous singer and actress, in my opinion, you definitely have to have talent. Spend as much time as you can working on your talents. Enter contests for singing and acting, take classes in singing and acting and spend time with other people who are in these fields. Get to know people in your area that might be able to help you in your career. Get to know the acting teachers, the producers of plays or local theater and the singing coaches. These people will have connections with professionals who might be able to advance your career. Get an agent if you can. Work hard and enjoy every minute of it.
To become a famous singer or actress, have a record of yourself doing your best performance and place it on the internet. There are several sites for upcoming artists and actor/actresses. You never know, you could catch the attention of someone who could catapult you to success. You could also find gigs in your area and volunteer. Besides building a network, this will help you get the feel of being on stage.