V1UHOH

Many ways to skin a cat, but here's my typical airliner build-
1. Dry fit parts!
2.For smaller scales like 1/200, I'll usually begin by backfilling cabin windows using Milliput as well as installing nose weight if needed. For larger scales, I'll leave the windows open and use Crystal Kleer to fill them in once decals are applied.
3. Assemble fuselage halves using plastic weld. My favorite is Ambroid Pro Weld. Holding the two halves about a millimeter apart I will apply the weld to the seam. Since it is a liquid, capillary action will carry it a few inches down the seam.
The two halves are then pressed together, creating a ridge of melted plastic along the seam.
4. Once the entire fuselage is complete and dry, simply sand the ridge away and the seam is gone. If a seam is still showing anywhere I will use some Mr. Surfacer or putty to fill the rest.
This also has the advantage of greatly increasing the strength of the model over tube glues, effectively creating one solid piece.
Be careful around panel lines. Aggressive sanding can sand them away, particularly if they are raised instead of recessed. Not too critical on smaler scales since they would be invisible from that distance anyway.
5. Next, the windows are sanded flush with the fuselage, then the entire fuselage is sanded smooth using increasingly higher grit wet/dry sanding sticks followed by a polishing stick. A wet sand is essential to carry the plastic away from the sanding stick and keep heat away. You can actually melt softer plastic usuing an aggresive dry sand.
6. A primer coat is then applied to prepare surface for painting, as well as spot any remaining surface imperfections.
7. Fuselage is then painted depending on scheme to be applied. I generally have more luck spraying the bare metal on the entire fuselage, allow it to cure then apply the colors, much like they do on the real thing.
8. I then do pretty much the same thing with the sub assemblies like wings, engines, etc using Cyanocrylate. Those come with differing dry times. For complicated assemblies it's not a bad idea to leave yourself a few minutes to properly position parts.
9. Decals.
10. Assemble the major parts
11. Final landing gear assembly.
12. Clear coat. My favorite is Future floor wax.
Just one of a thousand different ways, I'm sure everyone here has their own tricks and tips. The most important thing to remember is that if it looks good to you, then that's what matters!
My "must have" list for the workbench-
Milliput
Airbrush
Ambroid Pro Weld
Plenty of fresh X-acto blades
Miter box with saw
Plenty of wet/dry sanding sticks (Squadron is my favorite)
Scriber for panel lines
Various types of CA
Crystal Kleer
Elmer's glue (dries clear, good for etched details such as pitot tubes, antennae etc.)
Micro Sol and Micro Set for decals
Toothpicks
Various detail brushes for smaller details, decal solvents
Various colored model railroad weathering powders
Evergreen Styrene sheets of varying thicknesses
Hemostats and clamps for handling small parts
And much more!