Need help!

[Lands Of Terraria]

Hey there guys, I'm very new to this website, so I'm not sure if this is the right place to post this.

So, I want to build a dark themed castle, however I suck at building.
I lose ideas and organization when building, and consequently, my creations get messy, and I can't seem to 'fix' them.

What blocks should I use? Something that will help me not fail when building, like a pattern to help me do things right.

I have every single item on the game(all legit, not including removed items).

Thank you all for the help!
PS: I won't be answering comments in the next 6-8 hours.

Edit: My Terraria is saying that my xxx.player file was created by a newer version and cannot be loaded. This is making me really sad because I had Dungeon Guardian Pet, and it took me so many tries to get it.

 

[Quazariax]

I have a few tricks you could use, and you can see some of them in my latest build collection below in my stuff.

 

[Lands Of Terraria]

I have a few tricks you could use, and you can see some of them in my latest build collection below in my stuff.

Sure, I'd be glad!

 

[Surfleapard]

well there is blocks like demonite brick and ebonstone brick.
even more.. obsidian brick, iridescent brick (ash and mud), titanstone, even asphalt. and more but im not gonna say all of them