Where do the great creative ideas for advertising or websites or exhibition themes come from? I can tell you that "a committee" is low on the list of answers.
Although a great idea doesn't care who has it, some people spend most of their lives thinking of creative ideas for a living. Designers, art directors, copywriters.
There's no magic formula. But, it helps if you follow some basic rules:
1: Write down everything, even the ideas that you know are bad and going nowhere beyond the waste bin.
2: Never simply copy another idea that you like and try to shoehorn into making it work for your product or service.
3: It's OK to be nervous about an idea. If it's truly creative, it is probably breaking new ground. If it doesn't work, you can always revert to something 'safer'. Be prepared to fail.
4: Forget the budget. You can buy high production values by chucking money at the worst of ideas. But if you only have a small budget to play with, make sure your idea is brilliant.
5: Have fun.