If you stick with specific conventions and rules about time travel it isn't that hard to do. Movies like Looper and Project Almanac completely screwed it up by introducing a magical element that really shouldn't ever be in there. As long as you stick with the rule that things you do in time changes nothing about the timeline you come from, you're fine. Fucking with time may branch the past you're in. And it may end up further away from creating any future resembling where you came from. But it shouldn't change anything about you or any physical objects somehow magically before your very eyes. Stick with physics and it becomes a much easier element to deal with. You go back and kill your grampa before you were born. You don't disappear. There you are looking at that body and nothing happens. Because all you've done is created a new timeline branch. You can go back a few minutes and kill yourself. Then go back again and help that previously murdering you bury the body. Now you live in a timeline where you died and two of you live on. No magical disappearing people or limbs or photos. Those kinds of things are just based on bad assumptions and nonexistent physics.