Have you looked into PayPal Here - you can be mobile and accept credit cards - you will need a PayPal Business Account and a compatible device. You will also need a WiFi connection where ever you are at. Basically if your smart phone can connect to the internet where ever you go, the app will work. I don't believe that the app stores the customer's credit card details so you would need to swipe their card each or manually enter the details each time. As for manually entering your customer's credit card details (no card present transactions) note, there is a higher fee to do that. Fees are shown here.
There are other products out there that are similar to PayPal's product. For example there's Square - Square does have an off line feature which can come in handy should you not have an internet connection and I believe it can also store customer's credit card details. You can do manual inputs and funds are usually deposited into your bank account the next business day verses PayPal Here which does have deposit delays.
Check out the comparisons - there's several reviews out there - here's one. And here's another.
