I decided that I didn't want to deal with the moat building part, so I found a very large pond and then started building in the middle of it.
(Very large pond does not necessarily = lake. It was only 1 block deep.) It worked pretty good at first, but then somehow it got screwed up. Water flow was totally ****ed but only on one side. Caused
much butthurt.
Anyway, here's the progress I have made on the outside

and the inside

I left the center stripe grass because I intend to replace it with red carpet (red wool). It would be a pain in the ass to dig up the dirt then replace it with smooth stone
then mine it up and
then replace it with red wool. So for now, it is the fairway.
Those towers are far from finished.
I haven't thought much about the interior. All I know is that I want a red carpet and a double staircase leading up to the second floor. I'm not an architect, so I have no idea how I should lay out the rooms. I also don't know how I should space the windows and how big to make them. I would kind of like some suggestions from you guys on those two things.
Um... other details about my castle: When I complete the towers, I would like for each one to have a crown top. I discovered that if you place stairs just right, you might can accomplish this. I would also like to have a taller central tower. With a pointy top.