Hello, Tatomatoboy, Here!
I Made this a while ago, I'm just going to say it now,  not very good on the exterior. I am gonna write some tips, there is going to be a download, but DO NOT COPY WITHOUT MY PERMISSION.(This means to use it and post, If you want to just look around or change it you may, but even if you change it, you may not post. READ THE RULES OF PMC)
This is an interior example,so I didn't really pay attention to the exterior (Do Not Say Anything About How Weird It Looks In The Comments).
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• The floor of the cabin looks best if it doesn't look the same as the walls, this creates a look of a "Carpet" without using the carpet block.
  
• Use Quartz slabs for the roofs, and also don't make it flat, this represents the overhead baggage compartments.
  
• To my experience, seats look more like seats if they are two blocks long, and one block and a slab tall, the slab looks like the head rest, and the block is like the back of the seat. (Stil put a stairs, or whatever you use for seats in front, that is the 2nd block in the "2 long" part.
  
• Avoid Over-Detailing, I've done this many times and had to restart on the interior, dont change colors rapidly, and NEVER let restone show. FYI: DOnt let the livery on the roof show, just use the slabs to cover it up(From the inside :D)
  
• Don't destort the cabin shape, either make your edges move one row at a time like this: I -> I, also, build the lavatories at the end into the tail section of the fuesalage, if you have the space.
  
  
• Always have a below baggage compartment, it helps with the shape of the aircraft, if you dont, then your aircraft's bottem should be pretty flat. (No one wants that! o.0)
  

If you think this should be i the blog section, then your right, but I added an example that I wanted to use with this post.
Take A Look At My Other Builds! It Want Hurt You! :)