You can go to annualcreditreport.com and get a free copy of your credit report. If you find errors, have them corrected to maximize your credit score. You are entitled to one free copy of your credit report from each of the three credit bureaus each year, but they are free only from this one Web site source.
When selecting a card, you should have an idea of what you are going to be using the card for. For example, you might want to use your card mostly for gas and food purchases and are seeking cash back for those kinds of purchases. On the other hand, if you have a business and travel a great deal, you may want to get frequent flyer miles.
Once you have narrowed the field to only those types of cards benefit your needs, you can choose the card that best suits your preferences according to such things as annual fees and purchase APR.