It would be better if you shared a pic of that "ugly mess". That said I think that it should be fine (rule-wise) to ask it here.

For now, tips that I can give you:

• Focus on a theme for that build. The simpler the theme, the easier to get.
• Find good combos of blocks, and use them somewhat consistently for a feature of your build. For example: I personally like building walls with stone bricks + wood (it's cheap for survival, and it looks good), while the roof is mostly Nether bricks;
• Don't fight against the terrain. Some terraforming is fine; but flatting it all out will make your build look out of place.
• Use pictures for reference. Copying is 90% of creating.
• Too much detail is as bad as too little. Find a good balance.

Just post pictures or a video or whatever there’s not need to ask permission first.

When I'm unsure about how tackle a build I use reference images from Google or Pinterest, sometimes completely copying them and other times combining different elements of builds together to make something new.

I imagine it’s fine to ask for a critique. Where I think it starts becoming an issue, however, is if people spam the community for every little detail through multiple posts.

I learned this technique from a video, I don't remember who the author was.

Their idea is to start by building hollow cubes of somewhat random sizes, each connecting to the other and possibly merging (some parts of a cube inside others). Once you have enough cubes, you use those as the skeleton to build the final structure. Square-ish cubes become rooms, tall and skinny cubes can become stairs, really big cubes can be multi-floor open areas. The hollow cubes act as a canvas with structure, so that you can "paint" your build on something more than just empty air.

In general, there's a tutorial on the Minecraft wiki just for adding beauty to constructions, and the Construction category on the tutorial page has other tutorials for buildings too.

There is a guide I used to swear by on minecraftforum.net, might be this one but I think it was longer

Not that I'm any good at building, but a common strategy I've seen on various YouTube channels is to have a rough reference picture for what you're working towards. An image search for something and adding the word concept or concept sketch usually gives back something good. It helps you remember the final look you're after.

Eg. Image search for desert castle concept

Nb. Ignore the sarcasm at the link, just using it to explain what I mean