How to build:

Open minecraft

Open creative world

Select a block

Aim at the ground, And click the right mouse button

Repeat steps 3-4 until some sort of livible shape is made

Try downloading some maps that are really well built and take a look around it. Look at the building technique.

If you like the building style, try repicating it on a new world and see if it looks good. Then take that style of building and apply it to some ideas!

I love how people are giving really long paragraphs about this! Makes this community seem really helpful and nice. Thanks guys !

Try and get involved in a big project. I wasn't creative or really good at building at all until I saw this big building project so I joined it and let me tell you this, I learned SO much from being a builder I that project in such a short amount of time. The trick is to be creative and try different things you might think wouldn't work. A lot of building is about block combinations. For example what block goes well wit what block. Sorry if there are any grammatical errors I this lol I did this on my ipad (still new to typing on it). I hope this helped :)

P.S. check out my account for some creative builds coming soon. I've started a little series.

Edit: Turbo is right. That helps a lot too.

Thanks
-Monkey

What I do, is I come up with a sort of idea in my head (I use real life pictures for my inspiration), and I let the idea sit there for a while. I'll come up with new ideas over time, but then after a while I try to sketch my idea down. Use your sketch as kind of a guide, but also allow changes as you build. The main thing with building something really cool it experimenting and letting something form it its own way, but also keep it on track. Don't let it "wander off", and also always keep sizes and proportions, as well as your original idea, in mind. Maybe this helps a little?

Yeah I can understand that. I'll try that, but I still won't deny a teacher.

Here's My Theory:
Experiment with different styles, see which one comes easiest and looks the nicest to you. Then I would suggest looking at great builds of the same style, and take mental notes. Then you should start building your thoughts into the game, and you will find out how you are at building. This is what most people, Including me, do anyways.