I heard that someone can be infallible by conquering their nafs is this true? And if so how do I do so? Do I just refrain from all sin? If this is really true then I want to attempt it where do I start? What are some tips?

You are able to achieve certain level of infallibility. Ways of doing it are:
1. Abstain from sins as much as you can
2. Make sure to do the waajibat
3. Be in the company of those who remind you of your duties towards Allah
4. Self audit and supervision