I vote for witnesses as I see them on posts asking for votes. If they seem like they care and deserve a vote - I give it. I've been here just over 3 months and I've voted for about 15 - so that means I'm not seeing posts that catch my eye from the others. I only rejected voting for one of them so far. About half my votes are write-ins. I'm not sure how much time and effort to put into this beyond looking when a post catches my eye.