I ignore friend requests if I don't recognize the name.
If I have interacted with someone, and the interaction hasn't been hostile, and the user doesn't seem like they'd be sexist, transphobic, or similar, I will likely add the name.
If I see a post from someone who has requested me, there is a good chance I'll add the person from the post.
If the person is a bigot, I will actually *reject* the request; people who don't interact with me are likely to be simply ignored.
Users who appear to be something other than a straight male are more likely to be added by me.
P.S. If you have sent me a friend request that is still pending, and you want to be my friend, please send me a message or post in a topic I'm likely to check; otherwise, the request will just have to sit in limbo *forever*.