1st of all try to find best training program which will lead you to catch main PM mindset which required by PMI. In my case I obtained Eduhubspot training program  which included about 800 questions (including situational and definition based). 

2nd as you know PMI has it's book PMBOK 6th edition. It's main resource for PMP exam preparation. A Guide to the Project Management Body of Knowledge (PMBOK® Guide) is the workbench of PMP exam preparation tools.

3rd Sample questions : Try to use questions from quality source, not just all and any questions from internet which will waste your time and PM mindset. In my case I have used Eduhub,

4th Other Resource : PMI source and other quality source from Internet, WhatsApp study groups and etc...

Note : The main idea here is to catch up PM mindset which required by PMI. Once you handle it you will pass exam definitely. And no need to memorize ITTO. Try to understand. 

Good Luck ! 

Zaur Ahmad.