Try reading other people's hubs to come up with ideas. Also look around in the questions, answers, and forums and see if something strikes you. You can also try freewriting to see if anything comes to mind. If you don't know what freewriting is, you are welcome to check out my hub about it. If you become aware of your surroundings, you'll start to see that there are endless opportunities to write things on! Then, when you get rolling, keep a pad of paper and pen nearby so you don't forget what you thought of!