A good tip for this Tuesday has to do with mail in rebates.
Have you mailed one in only to get a response that you did not qualify because the submission arrived late? I have a couple of times.
Now, I get out of the little silver zoom zoom, walk into the local Post Office with my in envelope rebate form. I ask for date stamped postage. It's the same as a stamp, costs the same but has the date it is mailed directly on it. The worker will print off a white label and stick it to the envelope, wa-la, you're done, for not much more trouble.
If you loose money in a rebate mess up, it's always more than the price of a stamp.
Your rebate return is documented by making a bit of extra effort.