My general sequence is:

1. clean the parts. Warm water and a de-greaser.  I don't do it every time, but usually
2. prime the parts, on the sprues.  I think it improves paint adhesion, and it helps highlight any flaws in the material
3. assemble the model.  Sometimes I can assemble much of the model and then apply my color coats. Other times I paint things on the sprues and then touch them up as necessary after removing them from the sprues
4. apply color coats.  For example, this would be the olive drab over gray on a USAAF aircraft, the color on the body of a car
5. apply a gloss coat to prepare for decals.  Not always, but usually. I use Future acrylic floor coating, and there have been times where I just applied the gloss where the decal would go.
6. Apply decals
7. Seal the decals as necessary
8. apply weathering as necessary, eg, panel line washes, dirt, smoke and exhaust stains, and similar schmutz
9. sealer coat, as appropriate.  Dullcote, or a gloss coat.

As others have mentioned, there are always going to be variations depending on the kit, the subject (airplane? car? armor? ship? figure?, etc), the materials used, and unforeseen things that come up.