Cancel free trials a day early!
I had signed up for a free trial with encyclopedia britannica online, because I needed to look up one article for a class. I made a careful note of when the free trial would end, and canceled it that day. Of course, this led to me being charged, because I'd have had to cancel the previous day to avoid being charged according to them. Their FAQ prominently says they don't offer refunds, but if you poke around a bit more, you find that on yearly subscriptions (The $70 ones) they DO offer refunds within the first 30 days after renewal. That was what I'd been charged for, so I called, and in less than 5 minutes had my refund. I'll have my $70 back in 'up to 5 business days'. So, cancel free trials at least a day before they end, and if you do get charged, call and ask for your money back!