I remember my first steps in OSM. I drew buildings using Yahoo images. How ugly they were! I spent hours, but they did not look like real houses, just some strange, crooked figures.

With JOSM it is much better!
Now I draw similar shape quickly and very approximately, press "Tools/Orthogonalize shape" and that's almost it. Sometimes it's needed to widen or to narrow the house.

Great thanks to JOSM community!