The number of creative apps is almost uncountable! For experimenting it’s advisable to start with free apps, some pay for service apps offer demo versions for a trial period. You will discover very quickly if you feel comfortable with the interface and if the app provides the necessary functionality and usability for your purposes.
Note: This website often refers to an Apple iPad because the author is using such a device. Of course other tablet devices can be used as well if the respective app stores offer comparable apps and the graphic features of the device are sufficient.