Often we're pressured to make decisions before we're ready, or we take too long because we feel we're not. Setting a time for important decision-making can solve both problems by providing time to think and a time when you have to decide.
Don't stress about trivial decisions. Feel free to make those quickly. Only spend time on the decisions that are particularly important. What you have for lunch is not going to alter your life forever.
Get to know yourself so you know your energy levels. When your energy is higher, this is generally the best time for you to make your decisions.
Get "out of your mind" and into your body so you can make use of your intuition and not make your decision solely based on logic.
For each option, weigh up the pros and cons.
Ask yourself: How do I feel about this? If your head and your gut are at odds, it's probably best to slow down, take some more time, and get more information.