1) Are You Ready: Determine if you have the time (this is a very time intensive process), resources (applying and/or traveling for interviews can cost a lot of money), qualifications/experience to make a competitive application for programs you will be applying to. If not, then you may want to consider waiting to apply until you do.
2) Picking Programs: You want to begin narrowing down a list of 5-15 (this varies a lot by interest, degree, and discipline) places to apply. You can do this by asking professors, checking the places where the research you are interested in is being conducted, consulting books that outline the different components of programs across the country in your field.
3) Make A Timeline: Determine when you’re going to complete all the necessary components for your applications : narrowing down your list of programs, polishing your CV, personal and/or research statements, obtaining letters of recommendation, completing the application itself, taking and sending in GRE scores, etc. Having a plan will help you get everything done in a timely manner.