Before you try to rack up reward points, make a note of what items are excluded. Thinkstock By Miriam Cross, Associate Editor From Kiplinger's Personal Finance, June 2015 It sounds foolproof: Use a rewards card to nab up to 6% cash back when you spend in various categories. But a surprising number of items are excluded. See Also: 9 Overlooked Credit-Card Perks Groceries. Warehouse clubs, such as Costco and Sam’s Club, and big-box retailers, such as Target and Walmart, rarely rack up grocery points despite their extensive food selections. Dining. You can collect on anything from sit-down restaurants to Starbucks. But if the eatery is housed in another venue—say, a hotel or stadium—your purchase may not count. Travel. Rewards might not include campgrounds, taxis, tolls or tourist attractions. On the other hand, you may score gasoline points for picking up a snack at the station’s convenience store. Movies are also a pleasant surprise. Most points are earned in brick-and-mortar theaters, but Discover counts Redbox and Netflix as well. If you earn bonus points for shopping at supermarkets or office supply stores, consider buying gift cards there for other retailers that don’t qualify. Or consider a card that returns a flat 2% on all spending, such as Citi Double Cash.