Ideas are everywhere. Are you still in school or do you have a job? Your social and professional circles are a great way to generate ideas. When you think of an idea, write it down immediately. I write all my new ideas down into a single text file. I call it my "sparks" file. The reason I do this is to not distract myself from whatever project(s) I am currently working on. I can always look back at my sparks file and re-read all of my previous ideas. If you look at an idea you had 6 months ago and you still think it's a great idea, then it's probably worth pursuing.