First of all, you need to calm down your mind to think about anything. The best way is to get a power nap which will make your mind calm and you will be in better position to innovate new ideas.
Try to talk things with other people and also give importance what they say. Then make an analysis by combining their thoughts with yours and you will discover many new ideas.
You should also keep meeting new people who are in the same field. Try to grab the chance of attending seminars and classes which will help you in knowing the ideas of other people. Take inspiration from their ideas and develop your own opinion as well.
The most important step that you should take is start spending time with creative people. You will learn a lot from them whenever you find a chance to spend a little time with them.
If you are unable to focus on an idea, just relax and try to think something else. It will give relax your mind and you will be in a good position to focus on a desired thing.
Brainstorming is an important aspect of creative thinking. Try to think out of the box about anything that you do on a routine basis. It will help you to discover new ideas and will help you in improving your creative thinking skills.