Some time in the future, or more likely in the past, humans and whatever other species of alien there is out there will have to deal with a temporal paradox. Because of this, we should plan in advance to discover what it is we should do about it.
What is a temporal paradox?
A temporal paradox is an impossible event that occurs because of time travelling. A good example of one is going back in time to kill your father before he met your mother. Because your father is dead, you would never have been born, so it is impossible that you could have gone back in time. And yet you did anyway. Another example of a temporal paradox, and this one may not count, is Milliways in "The Restaurant At The End Of The Universe" by Douglas Adams, an author I will assume that you are familiar with. In the event that you aren't, Milliways is a restaurant you have to go to the future to get to. While at the Restaurant, you happily eat dinner, watch whatever band happens to be playing that night, and see a wonderful view of the Universe blowing up around you. Then, everyone leaves, and the restaurant goes back in time for the next meal. And, this is the paradoxical part, no matter how many times you visit Milliways, you never meet yourself. Like I said, this isn't exactly a paradox, but it is worth mentioning.
How do I know if I'm in danger of creating one?
This is a tricky one. Ask yourself the following questions: (1) Is there evidence suggesting that you have time travelled? If no, then you probably have nothing to worry about. Just be a little careful, that's all. If yes, ask yourself (2) Have I travelled to the past? If no, you don't think so, then don't worry. If you're in the future then you can't endanger your past very easily. Instead, just calmly walk up to your future self or closest kin, remembering to write something down about this when you get back to the past, and request assistance. However, do not call yourself on the phone. It's a waste of money and time. However, if you answer yes to question (2), then you may very well be in trouble. Try to stay as far away from yourself and/or any factors that may easily effect your life. Here, it is almost definite that you will change something about the past, but hopefully it won't have a too catastrophic effect on the future. Who knows, it may be a good thing. Anyway, when you get back to your own time, remember that you have just jumped to the PRESENT:ALPHA. Before you travelled, you were in the PRESENT:PRIMER, as in the primary present. You will probably never get back to PRESENT:PRIMER, so get used to your new reality.
What should I do if I cause a paradox?
First of all, remember the motto of hitchhiker's everywhere: "Don't Panick!" If you have caused a temporal paradox, one of several things may happen. Currently, we don't know what, because we've not time travelled yet/then/there/now. One of several possible things are likely to happen. The different scenarios are:
(1)It's too late. Once you have caused a paradox either you will have to be wiped from existence, or the entire Universe will. I hope, I really, really, really hope that this isn't what happens. However, just to be on the safe side, be careful.
(2)Calmly jump forward to the future, hoping that everyone, including the fabric of reality, remembers that you exist. If not, look on the bright side: you have a clean slate, no one will know who you are, and you get a great new name: John/Jill Doe!
(3)Try to undo it. It's possible that scenarios (1) or (2) will occur, but they might have a delayed reaction. In that case, you will have a short amount of time to fix whatever it is you messed up. Conceivably, you could do this by travelling through time to stop yourself from travelling through time. Keep in mind that this is just a theory, though.
(4)Nothing will happen to you in the future. Perhaps when you went to the past, it was all an illusion, and you only changed the past then, and not now. When you don't think about it, that might make sense.
In closing. . .
In closing, remember not to blame the space/time continuum for the paradox you are in. It's not it's fault. It was made that way. It's either your fault, or the fault of the one who sent you back in time. Just try to be careful, because the world is such a bad place already, I'm not sure if I could stand it getting much worse.