4) Turn on Auto-save
ND has given some very good advice above.

I would add that you can also enable automatic save. Incremental save only saves a previous copy of your scene each time you save. With automatic save you can force maya to save your work at regular intervals. You can also set it to keep a specific number of saves.

So in my case I set auto-save to every 6 minutes and keep 10 copies. This way at any point in time I have up to a one hour backup of all my work in 6 minute intervals.

This has saved my lots of work in several instances where I have made immutable changes to a complex model and then realized that they cause major problems down the line but I was able to step back through my auto-saves and get back to a point before the offending changes.

You can turn on auto-save in the maya settings and preferences section.