Ok, my first tip might be something everyon knows....

I have a spot in my living room where I place all tax paperwork that comes in.  That way as soon as the mail comes in I have a place to stack it :)

My second tip may be something that is too late to do now but can help you next year...

Do all donations by check or credit card - whether it's church, or buying something from a kid's school, or a donation to an organization.  That way you have a record of all these donations even if you don't get a reciept (which you usually don't nowadays).  I know some people don't claim donations, but I do.