The admission process is quite a long journey that needs a lot of preparations as you will see. If you intend to begin your PhD in september of year `X' then a good starting point would be january of year `X-1'. This is the date you should start to seek information about the PhD programs and think about TOEFL and GRE exams. Depending on your level you may need to take courses, read about the exams and make some sample tests for yourself.
In may or june of year `X-1' begin to ask your friends studying abroad about their universities and the cities where they are living. In july you should send your requests for the application materials which would arrive around one month later, i.e. in august.
From september to november, you will be filling the applications, getting your recommendation letters and finishing any examination requirements you did not fulfill yet. The start of december is a good date to mail the applications since the deadline of the majority of the universities is around january.
Speaking to the professors directly or through your recommenders is a good thing to do before the faculty committee meets and makes its decision. You may start to receive replies for your applications in march or april. Some of these will be good and some will be bad. Concentrate on the good ones and ask around for information about these universities. When you make your final decision respond to your choice as well as the others (thank them for the opportunity they gave to you but apologize that you will not be able to attend since you have already accepted another offer).
From may to july, you will be making housing reservation, getting the necessary documents for your visa and asking about the plane tickets. Finally, in august or september you will be flying to accomplish your dream.