Just can't get good at building?

Hi @moo - don't despair, we all start somewhere and I suppose any kind of design comes more naturally to some. I can't add much to what's already been said - I'm my opinion the best way is exploration but also it's sometimes worth downloading lots you are impressed by and looking at how they've been achieved from a building perspective and have a go at doing this yourself.

The video tutorials are also good maybe if you're looking to achieve something quite specific in function/form.

I used to find images of buildings or houses online that I liked the look of and tried to re-create them as best possible. When you have to fully explore the features in order to achieve a particular look it can give you a better idea of what's possible when you're creating other lots.

Furnishing to make a space appear more realistic, cluttered and lived-in is also a big factor I think and takes AGES but can be really rewarding at the end.