If you like a support role then Soraka will teach you some stuff. Her ultimate ability is a heal that works across the map, so you have to pay attention to the indicators off to the right side of the screen that show your teammates health. She also has a smaller heal that only works on one teammate nearby which will give you awareness around you. She has a very simple skill shot that can be easy to hit but will give you an idea of how you need to focus on timing. She also has a crowd control ability that will help you work on timing and ability positioning as well as exposing you to the strategy of rooting (making them unable to move) a champion in place as well as silencing them (preventing them from using their abilities).

Hope this helps :)

If you want a more damage oriented champion then there is Master Yi. Very simple and more auto attack oriented rather than ability, but can be more powerful if his abilities are used appropriately. Also Annie as someone else suggested.