Open a book and turn to a random page then select a random word on the page. Now using this word, write down any ideas that come to mind. Don't judge them just write no matter how stupid you think the idea is. Go back to your list and come up with alternates to each idea you wrote down.
Ask "What if"
Ask this question on anything. What if pigs could fly? What if dogs could talk? What if I didn't have to go to work? What if I were a millionaire. You get the idea.
Get a group of people in a room and pose a question. Write down all answers. Don't judge them this is time to collect. Now look at your ideas and find the best three you've come up with.
Combine two ideas
Take two random words and combine them. Is there anything novel you've come up with. Take two activities for example "dinner" and "games." Start a club where you have dinner with a group of people and play some sort of game.
Think outside the box
This is easier said than done. The key is to look for completely different ways to do things as ridiculous as they might seem.
Go back to your childhood and use your imagination to come up with new ideas. Remember playing with toys, laughing running. Ghosts, fairies, Jeanies, witches, dragons, aliens.
Look at problems you've have and come up with solutions to them.
What annoys you? Others? Solve it and you might have a new business.
What tools do you wish you had? What do you wish it was easier to do? What do you wish you had, could be, could do?
These are problems that strike a core with you and others. Solve them and you might have a winning product or service on your hands. Track whatever you hate and use it.
Take any existing product or service and make it faster than the current method.
Make an existing product cheaper. Find ways of doing thing for less money.
Make something prettier. What's ugly? What don't you like to look at? Can you make it smoother, squarer, rougher, shinier, duller, better shape, different shape. Peacock it. This means you take away functionality just for people to see it. Can you package it better. Jeff Gitomer packages his books with rounded edges, high quality paper.
What if there were more of something how would this help or hurt. More food, jobs, friends... What do people want more of?
What do people want less of? How could product or service be better if you did less? How can you make it a competitive advantage? Less waste, pollution, time, fumes, effort, pain, loneliness, crime, death. Anything that's bad we want less of it.
How can you make something slower but better? Slow your walking to relax. Slow your breathing, rate of mistakes, decline, aging, anxiety...
What methods can you apply to you idea? Outsource parts? Drop all other goals? Set alarm reminder ever 15 minutes. Change your environment. Explore new stimulation. Work in a different room. Work with crayons or markers. Communicate without talking. Do it in the dark. Create while hanging upside down...
If something takes 5 steps can you do it in 4? Can task be automated? Can you create templates, checklists, tools.
Can you make the product or service more convenient? What if airlines picked you up at your house, screen your luggage, loaded to a van
Repurpose an idea
Look at word lists for ideas
Can you remove something to make it better? Can you change the order to improve it?
Look for Niche
Instead of selling X, sell X to group Y. Example. Don't sell shoes, sell shoes just for toddlers.
Put your idea to the paper, 3D printer, molding clay, storyboard. Whatever you can do to make it more real.
Get feedback from your idea as soon as possible and from as many people.
Make your product or service more secure. Can't be stolen, copied, hacked, etc.
Automation (Robotics, software)
How can you automate what you're doing?