Once you invite your spirit guide into your life, communicating with your guide is easy to do. For example, the moment I become aware that I have a problem, I ask my guide a question about how to solve the problem. (Related link: Your 'Spirit Guide') As soon as I ask the question, I release it.
During the course of my day, often times, the answer I requested makes itself known to me while I am busy doing other things. If the answer doesn't make itself known to me, at some point in time the problem simply disappears from my life for no reason I can explain or someone shows up in my life who solves the problem for me.
The key in communicating with your spirit guide is releasing the question after asking it. Holding onto a question, about a problem you have, after you have asked it, is a vote of "no confidence" in your spirit guide's ability to solve the problem for you.
Trusting your Spirit Guide allows answers to be revealed to you. Distrusting your Spirit Guide prevents answers from being revealed to you.