Listen, I'm definitely not an expert on this but I watch too much Air Disasters to be healthy, and now I'm going to give all of you my knowledge on how to survive a plane crash that you definitely aren't going to remember in a real plane crash.
So first off, let's start with how to do the brace position. Make sure your seatbelt is uncomfortably tight, so that way you aren't flung from your seat. Look for your nearest exit, and then get into the actual position. To get into position, you're going to want to lean as far forwards as possible, wrapping your arms under your legs. This helps as you won't be jolting around as much, and it helps to keep you in place as well.
Now for a water landing, otherwise known as a ditching(I think). Get into the brace position again, and once the plane has effectively landed you are going to want to grab your life jacket.
Remember: if water starts filling the plane, don't inflate your jacket!
Listen to the flight attendants and get to your nearest exit as safely as possible. Once outside you may inflate your jacket.
Since you're probably going to have to jump into the water, make sure you jump with your arms extended, one leg straight out underneath you and the other leg lifted up like a flamingo.
I don't know why, but that's the safest position to jump in. Now you're in the water, and the rafts are probably out unless people are still coming out of the plane. I believe the most common rafts are the ones made from the slides, so if you're the first one out, you may have to wait for a while. While waiting cross your arms and your legs, tucking your legs close to your chest. Your life vest should keep you afloat. Once the raft is in, begin looking for the ladder. The walls of a life raft are meant to be kept 3 feet above the water, and all you have to climb up is a flimsy rope ladder, so you're going to need to get all your strength to climb inside. Make sure you listen very carefully to the flight attendants and/or the captain once in the raft.
Great! You now know how to increase your chances to live in the event of a water landing! Let's go over what to do in the event a fire happens in a plane. If you see smoke, notify your flight attendants, seriously. If nobody else has noticed, congrats you saved your plane. If they cannot find the fire, you still probably saved your plane. It will land at the nearest airport, or if it is a dire situation, probably anywhere. Once you've landed wait for the flight attendants instructions unless they tell you to immediately evacuate the plane. Don't stampede out of it, and make sure to slap anybody trying to grab items from the overhead compartments unless it happens to be an animal(which would be illegal anyways). You're going to want to get out of the plane as soon as possible, since the fire was contained before, but the incoming oxygen will feed the fire more, and your plane will most likely blow up. Now that you're off the plane, run away as fast as you can, because as mentioned before, the plane might blow up.
One of the least likely events to happen to a plane is depressurization. In one case the propeller of a plane came off and cut it open, which is not good. That will never happen to you(probably), but even if something did happen to the plane, such as a door being opened or a window coming out, the oxygen masks will drop. You just have to buckle up immediately, put the mask on and pray the captains aren't dumb. You have 12-15 minutes until your oxygen runs out, and in that time you will most likely be put down to a safe altitude.