good . Always remember that whenever you start a project preferably save your files in maya's native "name.#.ext" format. Keep your machine always clean ,free from viruses.
keep on saving file again and again in increment. Most important when you have done alot of mesh work in viewport always arrange your objects by renaming them and adding them in layers. Try to group the objects so that outliner stay clean and make sure that there should not be empty groups or empty transform nodes in outliner if there are then delete them. whenever you optimize the scene from optimize scene size option its good, but sometime unused empty groups and transform nodes stay there in default cache of MAYA which are always visible in outliner. so delete those. If you follow these tips you will hardly face any error.

Happy rendering