Do Mindful Work
Here is a tip I learnt through my Zen practice that has helped me a lot when trying to come up with ideas and/or solutions to various problems.
If you are stuck on something and can't come up with a solution or idea, stop and do some mindful work. By work, I mean doing any task that doesn't require "thinking" and problem solving, it can range from washing dishes to taking a shower or doing some other manual task. Being mindful means that while you are doing this task you need to focus on the task. I know it's hard, it took me time to get there and I still find myself getting out of line. While doing the task just focus on the task at hand (describing to yourself what you are doing really helps) and let your subconscious do the work.After you have finished you will feel refreshed and some ideas/solutions will probably come up that you couldn't think of before.