How indecisive are you?
If your answer to that is 'very', then be careful. You could be driving your friends nuts! :) One of my friends is so indecisive, she questions everything to the extent of overkill. "Why do you think he said that? What do you think he's doing now? Shall I call him? Do you think she'll buy that car?"
Those questions (mind you, about people I don't even know!) are just a prelude to another set of questions about how she should act/behave. The frustrating part is, after all that, she ends up doing something completely different than whatever advice you've given her!
If you have problems deciding, just think it through in your head. Think of the pros and cons. Put yourself in the other person's shoe. At the end, most decisions, even if wrong, aren't fatal. With time, you'll get better at it!