Hello

Many people think their projects look bad so i hope i can help with that

Step 1.Plan you build,plan everything,if you have a team to build with plan who takes what tasks(when you plan your work they intend to become a lot better)

Step 2.When you have planned all of the work.start making a starting area to build in or if you make a build that is in the air make foundations

Step 3.When you have made the foundations you should start with the walls and roof.use details when you want someone to notice something like a wall but don't use to much details and especially don't use details when you don't want to have someone notice something like a mobgrinder or something.remember to keep to the scale it will make the build look better

Step 4.Now that the Building is finnished start with the interior decorate it.also when you build make sure that you build according to the style you use for example if you build modern don't use torches for lighting use glowstone or lamps

Step 5.now that you are finnished with the build you can upload it.use shading mods and texture packs to make it look better when you take your screenshots

Tips

Use slabs and stairs to make decorations

Use world edit voxelsniper and mc edit when you make you maps they will help you alot.mc edit also have filters so you can change spawners and so

To get inspiration you can watch other peoples builds and get ideas from them(but don't ever copy their work)

www.minecraftwiki.net/wiki/Tutorials/Furniture here some tips for furniture

Hope you find this useful good luck with your builds