When it comes to angels, I find it best to communicate with them simply by talking to them. Your guardian angel, as well as other spirit guides, will always be by your side, so just let it know you want to start to bond with them. Meditation helps as well, if you got the time, and pray to him/her so they can let their presence be known. With time they will come to you, so be observant of any signs they might give you.
I agree with the above comments. And as angel magick is my specialty, I know what I'm talking about. (This is based on 12 years of experience in magick, and 24 years of experience with angels).
So, also based on my experience, the best way to contact your guardian angel, as SergioC. said, is meditation. And be aware that they might not answer you in words. They also might not answer at all. If it is not the right time in your life for you to contact your guardian angel, they won't respond. But if you keep your eyes open, and pay attention to your surroundings, within a week or so you should have recieved some sort of sign. And signs can be little things that you wouldn't normally pay attention to.