1. Meet new people. Even old people.
When you speak, you can't learn anything new. Creativity is often a team sport. When you share ideas with other people, you get feedback, and your ideas improve. Whenever I need to improve an idea--I run it by other people. Even if they don't add anything to my ideas, just the fact that I share them improves them. Furthermore, when you meet other people, you get new ideas. You hear of new problems, for which you may create new solutions. My most creative days are those in which I meet other people. It doesn't matter what the context is. Just meet people. Every day.
2. Learn something new.
The process of generating new ideas relies on filling your head with old ideas. Whether you watch science fiction movies, read a book, or listen to a podcast, those are filled with ideas. The more of those you expose yourself to, the more potential combinations your brain can generate. Combinational creativity is based on the connections made in your medial pre-frontal cortex between ideas. Adding one idea to the n ideas already in your head adds n possible new combinations. The next idea would add even more. Learn something new every day. Decide how, and mark it on your calendar.
3. Try, or create something new.
Another type of creativity relies on experimentation, especially when you don't know what to expect as the outcome. Put an activity on your calendar that you know how you start it, but you don't know how it will end. It is guaranteed that you will learn something new. Alternatively, schedule the creation of something new. For me, it is the writing of an article, a chapter in a book, a Facebook post, a video, a new logo (yes, I have many logos...), or a new page to one of my websites. Consistently creating new things is one of the best ways to make you consistently creative. Your brain gets used to it. Even if some of the material you create is not as great--keep doing it.
4. Schedule down time.
Ideas combine in your brain during down time. Not when you are watching TV, checking email, or drinking coffee. Make sure you set time aside to daydream. Don't' confuse that with reading, or talking with other people. Your emails can wait, and so can the news. Even if it is only 15-20 minutes a day, have "down time" on the calendar. And be prepare to write ideas that come up. This, by the way, is why we get our best ideas in the shower, or when we drive the same route to the point that we drive on "auto-pilot."
5. Do something intense before that.
What intensifies the power of down time in connecting ideas is the stark contrast between it (down time) and the activity that preceded it. For me, it is shooting, flying airplanes (full size or model), or riding motorcycles. For others, it can be as simple as exercising or simply walking. Whatever it is, do that before you schedule your down time. And yes, your down time can simply be the shower you take afterwards.
If it's not on the calendar, it ain't happening.
It is important to schedule those activities in your calendar, on a daily basis. It's easy to say you'll get to it, but reality is that you might never do it otherwise. There are always other, more pressing matters to tend to, so you put those aside. You often don't have realistic time estimates for different activities, and don't get to do everything on your "to-do" list. As a result, what's not on your calendar ends up being prioritized, re-prioritized, and re-prioritized again... Put it on your calendar. Give it different colors. And just do it!