Tips to improve looks?

Hello,

I'm terrible at making crafts look good, mainly getting different parts to connect smoothly. Take a look;

You can see the whole top/window section doesn't smoothly fit in with the middle/door section.

And for this one, the windows have a bad shape, and they have a visible line in between them. I'm thinking about panelling with tiny pieces, but it'll be hard to get the sides to connect nicely.

Here, I don't like the shape, and again the parts don't connect smoothly, but I'm not sure how to improve it.

If anyone has tips on how to make it look less ugly, please share them.

Thanks