I've got this habit of using rm and Shift + delete when I come across a file that I'm not using. It's been costly at times when I've removed files that I would later need. Now, since I've paid dearly a few times, I've decided that the following are a must:

1. alias rm='rm -i' in ~/.bashrc
2. NEVER USE SHIFT while deleting
3. Since I spend most of my time on the console, install ptrash or trash-cli and make use of these when you have the urge to delete a file. (trash-cli seems better at a glance here)
4. Take time out in a fortnight and empty your waste basket.