Decide how you will learn Russian. Will you take classes, hire a personal tutor or teach yourself with books and software? Having a skilled teacher, whether it be in a classroom or with a tutor, is by far the most effective option in the long run. Books and software are great if you are planning to visit the country as a tourist or for a short business trip. However, if you want to learn to speak the language at a high level, you will need a teacher for a least some of your study. Keep in mind that teachers who are native speakers are better for learning pronunciation, but a teacher who is a native speaker of your own language will be better at explaining grammar concepts. Thus it is helpful to have both kinds of teachers at different times in your study.
Build your vocabulary. Outside of class and regular lessons, be obsessive about building your vocabulary. Make your own flash cards with Russian on one side and English on the other. Arrange them into random stacks and carry them everywhere you go. Any time you have a free moment, pull them out and work with them in both directions (Russian to English and English to Russian).
Make friends with Russian immigrants in your area. Many will be happy to exchange Russian lessons for English lessons.
Consider an immersion program. As you become more advanced, consider enrolling in an immersion program. There are several based here in the U.S. They generally take place in the summer and last about 2 months. During this period, students are required to speak only Russian, even outside of class. These programs often help students make large advancements in a short period of time.
Enroll in a study abroad program, in which you spend a summer, a semester or a year living in Russia and attending daily language classes. Such programs will not only help develop your language skills but also help you to better understand the culture. Many U.S. colleges and universities take part in such programs and will even offer credit for participating.