If you want, I could give you a link to a website where you can find out how to build tons of types of furniture. It's too much to post right here. Do you want me to?
If you have the capabilities, it would help to use world edit or singleplayer command for larger builds if you intend to copy and paste something somewhere else.
World Edit or Single Player commands are good for shapes, filling in, replacing and a variety of other things that can help you build.
Please read these two threads:
http://www.minecraftforum.net/forums/minecraft-discussion/suggestions/2572194-please-read-this-before-making-a-suggestion-v2-0
http://www.minecraftforum.net/forums/minecraft-discussion/suggestions/44180-for-the-critics-ftc
It's just you have to start with the basics.
I can't afford full computer version,so I use PE
I built an unwater base.
I would show a picture but I ahve no idea how.
I agree. You only get better with practice.
Depth
The depth of the building is very important, saying that a flat side of a build doesn't look very nice
Detail
The block combinations are key for building. Blocks good for detail for slabs, stairs, fence and cobblestone walls.
Shapes
Don't make your build only square or only circle, put some variety of the shape of the build/building
World Edit or Single Player commands are good for shapes, filling in, replacing and a variety of other things that can help you build.