Before opening any card make sure you will be able to pay off any card you open. The moment you miss payments, is the moment where none of these rewards are worth it. Next, look for a card with no annual fee and make a couple small purchases a month and pay it off, this will help you build positive credit history.
If your out of college and employed or an adult with pretty good Credit, check out the Chase Freedom (my link)
Highlights: No annual fee, 5X points in rotating categories, $150 if you spend $500 in the first 3 months
Citi Highlights: No annual fee, 2X points on dining and entertainment
Discover Highlights: No annual fee, 2% cash back on restaurants and gas, $20 credit each year for gpa over a 3.0