Hey there :3

So I'm going to start with talking about your terrain. As far as I can see, you have none.
Atmosphere can be created through various ways, but in terms of terrain, I think it's widely made through cliffs and layers to the grass. This can be something simple like this:
http://www.reverieinteractive.com/BetaGames/Minecraft_Clone/MCCloneTech1.PNG
This is a little more complex than what I was aiming for, but it shows you the layers well. Some can be jagged, some can be smooth. You can make as many as those amounts of layers, or you can only make like 3 or 4, it's completely up to you. That image is justa  good demonstration of how you could make natural looking flatter terrain to build structures on!

You could go more creative like this, however:
http://i.imgur.com/6JAFz6I.png
(Credit to Awesomeaki99 - Spark plot)
This is slightly more in depth terrain making - it shows you can multi layer and also adds way more atmosphere. It gives you a larger and more creative area to make a structure on as well, and just looks nice.
And like some have done, but they're more experienced builders, you can make this style of cliff higher, and make a really tall plot - Have a fly around spawn and I'm sure you'll see what I mean.

Secondly, your organics; again, you have none.
So in case you weren’t aware, organics are basically things that are living, I guess – easiest way to put it. The most common organics are trees. Trees can be daunting at first to make, but they get easier. I used to suck, but then I met a guy who is well known in the community for making trees. His name is Plutouthere - https://www.youtube.com/channel/UCLUKySjsOfU9jcjYyFJWk2A/videos - there’s a link to his YouTube, where he has a couple tutorials on creating different kinds of trees. Check that out and see what you think.
Other organics that people tend to make can vary from people, animals, custom flowers. – I tend to see, on plots with high terrain, a lot of custom flowers.
Human organic: https://imgur.com/IkxAK0y
(Credit to TheDanishDreams)
Flower organic: https://imgur.com/0tklU0D
(Credit to Brad)
This is a really detailed example, as he’s created a large toadstool too. But it goes to show you that you can make anything living and it’ll work on a plot, as long as you give it purpose! ^.^

Lastly your structure. I think it is a nice start, you have a nice shape but very minimal detailing on the walls, and way too much detailing on the roof.
The structure is usually, more often than not, the thing that is given the spotlight on a plot. If not, and the terrain is the main focus, then the structure still comes into play.
There are two main aspects to a structure that you absolutely HAVE to consider when building – depth and detail.
Depth is the use of layers. Simple depth is created through the use of a frame. A frame can be made simply, or it can be more creative.
Simple frame:  https://imgur.com/ONsoRxh
More complex frame: https://imgur.com/20eZjP8
(Credit to DuttYGilberT for both)
Those are just two examples, with no palette, to demonstrate the difference that can make. You can use that on all four walls and make a small house, or you can make a larger structure with the more complex frame in the image.
However, these are both very basic still, we want you to be as creative as you can be!

Detailing is the use of slabs/stairs/cobblestone walls/fences etc to show details and a pattern or interesting aspect to a build. Small detailing like fences/trapdoors tend to be used on smaller structures, like houses or towers. And slabs/stairs tend to be used on larger structures, if not full blocks. Detailing can be tricky, as you don’t want to over detail. You also want to bring the detail into the depth and create multiple layers of it, instead of just one layer of detail in front of a flat wall. Again, I advise you to fly around spawn, have a look at some of the plots in the black carpets around the very edge and see the type of standard.
I want to stress this now that you don’t have to build that well in order to rank. Most of those builds around spawn are exceptional and we do not expect this of every single person who comes on here.

So your structure that you’ve made doesn’t show much depth or detail.
Start off with an easy small house build on a small plot I think. Using the basic terrain I showed you, or if you want to implement the cliff style into it too, you’re more than welcome.
You’ll need a roof, however. Roofs can also be tricky, but there are many styles of roofs.
Medieval/Elven style roof: https://imgur.com/a/Lr9Ab#0
(Credit to DuttYGilberT)
Rounded roof: https://imgur.com/WgvhAUP
(Credit to pomomomo1234)
Oriental Style Roof: https://imgur.com/vo2A2Bu
(Credit to iHaya)
Pointed Tower Roof: https://imgur.com/csiGTVH
(Credit to sarazon)
Hopefully those roof styles give you some idea of a route you’d want to take. They are very different styles of roofs for very different styles of builds, so I hope you find the right one. My only advice for a roof would be not to use all stairs/slabs. I think you need to use full blocks, with maybe some stairs of slabs for detailing. I think it’s always nice to have an overhang too, so the roof doesn’t match up with the wall. And lastly, make sure your roof is a different block to the walls, so then there is a definite difference!

GOOD LUCK!
I’m sorry this is super long but hopefully you’ll learn from it and make a FANTASTIC plot!
- Dutty :3