The most important thing is to be serious about it and make a studying schedule and abide with it.
It took me 3 months and few days after i got my preparation course to pass the PMP exam. I didn't believe firstly that i was able to do it in this short time. And was really happy that i got the certificate in this short time of studying.
Be serious about it and use any free time of your day in study, according to the schedule you prepared already.
In order to prepare this schedule you have to know first your self , i mean your ability to study and your available free time for the coming weeks and of course the sources that will study from.
For me i read the materials which i got from my preparation course and i read the PMBOK 2 times which is eally important to read) and a book called head first.
And in order not to keep my self studying for forever, i booked a date for the exam to give my self an end date for this studying project.
And thank GOD i passed.
Good luck to you too.