"In the past, I have failed to get to know my neighbours before they moved away."
If you do want to make it a habitual action, you can say:
"Sometimes, I fail to get to know my neighbours before they move away."
As you can see, I have used "to get to know" rather than "to get familiar with". The former is much more natural. Some people will say that "to get familiar with" means that you become quite intimate with someone, more than just friendly.