What is the Most Scientifically Accurate Theory for Afterlife. NO RELIGIOUS ANSWERS!?

Is there a certain way you must act, or is everyone from hitler to Mother theresa going to the same place, whether it be another dimension or nowhere, which is still something if you think about it...I'm bored of this current life but am nervous what comes next is worse. im not suicidal just curious as to where i'm going and if anything i do affects it. If the latter were true, I'd assume life would come with a rule book, which it doesn't. Societal laws are man-made and are not what I am alluding to.