This tutorial is for people who are not good at fighting in Minecraft and want to defeat the Ender Dragon without losing valuable equipment. It is based on my experience in Minecraft 1.11.2

I am a builder and explorer in Minecraft and fighting does not normally appeal to me, but, I wanted to defeat the Ender Dragon. I watched some videos, read some advice, got all geared up (with backup equipment also) and proceeded to lose everything.

The trouble is that most of the videos and articles about fighting the Ender Dragon are not written by noobs, and so they will tell you to take all this equipment and potions and such, which works fine for the more experienced fighters, but can be very wasteful and heart breaking to noobs to see their hard earned items disappear.

My problem was: it is very difficult to manage watching out for the Dragon, avoiding Endermen and Dragons Breath, and looking for your loot you dropped when you died all at the same time when I was not used to being in fast action fighting situations. Between getting knocked into the void and not being able to find and recovery my stuff in time, I ended up losing a few sets of enchanted diamond armor, power III+ infinity bows, enchanted diamond swords, wasting numerous potions and golden apples, etc. I thought, there has to be a better way!

Then I tried out a new tactic and it worked. The basic tactic is outlined below and it is founded on the idea that you are going to die multiple times anyway. This tactic doesn't use any enchanted weapons or any armor. You can use it as-is if you are as bad a fighter as I am or you can modify it or add to it to make it suit your style better.

Prep:
Make a bed near the End Portal and sleep in it.
Make chests and fill them with stone pickaxes, dirt, bows, arrows and iron swords (stone swords should work also, just takes longer,) and maybe some extra supplies to make more of these items if you run out.

Stage 1:
Equip yourself with a Stone Pickaxe and half a stack of dirt. That's it. No armor, no food, no weapons, or anything else.
Enter the Portal and find the ring of obsidian towers and the Dragon.
Locate a tower with iron bars on top.
Pillar up the side with the dirt.
Break the bars with the pickaxe, then use the pickaxe on the crystal.
You will die in the explosion, but that is ok, you probably died many times just getting to a tower and climbing it anyway.
As you are doing this, practice avoiding Endermen and learning the Dragons movements, but mostly focus on getting the caged crystals destroyed.
Each time you die and respawn by your bed grab another pickaxe and dirt and repeat.

Stage 2:
Equip yourself with a bow and half a stack of arrows. That's it.
Now focus on shooting the remaining crystals on top of the towers while avoiding the Dragon.
If you are getting better and start running out of arrows before you die, then grab more arrows the next time.
Continue learning how to avoid Endermen and predicting the Dragons behavior, but focus on getting all the crystals destroyed.
Each time you die and respawn by your bed grab another bow and arrows and repeat.

Stage 3:
Equip yourself with an iron (or stone) sword. That's it.
Go to the ring of towers and try to stay within the ring.
Avoid the Dragon as much as possible (you should have a little practice by now) and wait for it to land in the center.
Go behind the Dragon and continuously jump and hit it with your sword. Remember to wait for the weapon cool-down.
Continue this avoid-attack cycle until you or the Dragon dies.
Each time you die and respawn by your bed grab another sword and repeat.

That's it. You haven't lost a single precious item.
The pumpkin helmet is not necessary (unless maybe you are getting killed by Endermen every single time.)
If by stage 3, you feel confident enough that you can recover your items, then you may want to try some armor and a better sword and just recover them each time you re-enter the End instead of grabbing a new sword each time.

Hope this helps some of those noob people like me who are not great at fighting.