I am here to offer some tips on two of the big Rs of the holiday shopping season: rebates and returns.

"There's a lot of variability with how manufacturers and retailers handle this," said Karl Quist, president of PriceBlink, an online price-comparison tool. "It reflects different philosophies of customer service."

As in, some businesses treat people fairly and generously, and some don't.

Rebates are one of those things that sound a lot better than they are. That's intentional.

The most common approach is for everything to be done by mail — old-school snail-mail, not e-mail. Needless to say, it's occurred to more than a few manufacturers that many people won't go through the hassle.

It's estimated that 40 percent to 60 percent of rebates go unredeemed. Just in case, though, manufacturers often make the process unnecessarily cumbersome by requiring lots of documentation to get the rebate wheels spinning.

According to the Federal Trade Commission, the required documentation typically includes the original sales receipt, the bar code (aka the universal product code) from the box, the rebate form and your contact information.

"In most cases, this paperwork must be sent to the manufacturer or retailer within 30 days of the purchase," the agency says. "Consumers generally receive their rebates up to 12 weeks later."

Sometimes that promised rebate fails to materialize. This is when consumers have to start being persistent and jumping through hoops.

Be prepared. Always make copies of all rebate paperwork before mailing it off.

To really cover yourself, use your smartphone to take a picture of each document, as well as the envelope you're mailing them in. Heck, even take a selfie of yourself handing it to a Postal Service worker. The more proof you can muster in a rebate dispute, the better.

If a company still won't honor its agreement, you'll have to escalate things. Contact the FTC and the state attorney general's office.

That won't guarantee a satisfactory outcome, but it keeps the heat turned up. As a last resort, consider dragging the offending manufacturer into small claims court.

Returning an unwanted item also can require a good deal of stamina. It all depends on the merchant.

Some retailers make returns a breeze — you bring in the item, hand it over, show a receipt, get your money back: No questions asked. I try to patronize such businesses as much as possible. They clearly want me as a return customer.

Then there are merchants that seem to deliberately play rough.

"Return policies should be a big consideration for holiday shoppers," said Elyssa Kirkham, who helped conduct an annual survey of return policies for GOBankingRates. "Two-thirds of people return at least one holiday gift."

Again, ask in advance about a retailer's return policy. If you think the playing field isn't level, walk away.To be safe, always hang on to your receipts for the big stuff — anything that costs more than $100, say. I toss them into a shoe box and sleep better at night knowing that if I need a receipt for something, there's a good chance I'll be able to find it.

David Lazarus is a Los Angeles Times columnist.