Wordpress has a very useful feature which will automatically save your current draft every 30 seconds, as you type and you will not even notice. What many people don't know is that you can change the time settings on how often Wordpress auto saves by adding a setting in the wp-config.php file.
This will now change Wordpress to autosave every minute instead of 30 seconds.
Changing Post Revisions
Along with auto-saving your posts as you type Wordpress will autosave different versions of your current post, the default of this is 5 different versions but this feature can also be turned off or changed. If you want to increase the amount of revisions that are saved in your posts database then you can do this again by adding a line in your wp-config.php file.
The above code will make sure that there is a maximum of 10 revisions per post. If you don't want to limit this to 10 you can actually turn this feature off, but this means Wordpress will not store any revisions of your post. To turn off post revisions add the following line to your wp-config.php.