Don't allow paper to sit around in piles in your kitchen, on your counter top or in your car. If you have a post office box, open your mail beside the trash bin so that you only take home items you will action.
When you collect your mail from your letter box or mail box, spend a few minutes opening every envelope, recycle paper where you can, shred documents with your personal information on them (I keep a shredder by my office desk), cut out coupons you will use and make a pile of actionable items. Only keep papers you will need or action.
Allocate 10 minutes every day to action your mail/post, don't allow it to sit around your home reminding you of things to 'do'. Spending a few designated minutes every day will help you feel more productive.