Clip In Extensions?

Hey I've never owned extensions in my life but I am thinking about getting some. My only concern is that they're going to pull out my hair and I am trying to grow it out. The lady at the mall told me that clip in extensions won't damage your hair, but I didn't completely trust her because she is there to make money lol. So, to anyone that has clip in extensions, my question is if I am trying to grow out my hair should I wear them? Are they going to damage my hair?