God is loving and since we are all individuated parts of God, we also have the most natural attribute of love. Guides are other energies (you can see them as souls or other parts of God or All That Is) who have an awareness that service to others are really service to God and themselves given that we are all One and interconnected. Hence, these energies wish to be of service to us and they have agreed to help and guide us while we are, metaphorically speaking, veiled from our true divinity on the Earth plane for our soul growth and experience.

Many people have wondered how many guides we have and it is in our opinion, a futile question. Our guides on the other side is infinite, yet one. They are like an "energy soup" that may change from time to time depending on their agreements with us and our needs. Nevertheless, many people do perceive their guides as individuals and this is perfectly fine. They may or may not have names and it does not matter how we perceive them as long as they could serve us. Our higher self can also be seen as part of this guidance.

Everyone is capable of communicating with their guides, whether consciously or subconsciously. Some may communicate with their guides through various psychic abilities but we can all learn to "hear" them by simply "listening" to our intuition (i.e. feelings). To simplify matters here, if something feels good and expansive, this is a nudge to take it on. If something feels bad or uncomfortable, you ought to reconsider. Nevertheless, we should be aware that we have free choice in everything and there is also the influence of the negating self/ego that could be sabotaging us.

Due to our free will/choice, it is also important to ask Spirit (or whatever name you feel comfortable with) for help. Otherwise, sometimes they cannot help because of interference with our free will, lessons or paths. The help being rendered may also not be what we expect or to our timing, but know that it is always for our highest good. Having said this, it would be good if you are specific in your request for help.

Guides often communicate to us through ideas, thoughts, feelings (as above) or through synchronicities in our lives. For example, we may keep seeing or hearing the same words at signboards, magazines, TV, from friends, or perhaps a book may literally drop from the shelf in front of us. Pay attention!

To top it all, consider the possibility that a part of us could be a guide to other souls!

^Note This discussion is only on Spirit and not on humans who call themselves spiritual masters.

Further Reading

Kryon Q&A on Guides
http://www.kryon.com/inspiritmag/archives/Q-A%20archives/2001-Q%26A/q%26a-print.html#1

Working with Masters
http://www.maitreya-edu.org/teachings/whatdowedo.php

FAQ about Spirit Guides
http://members.aol.com/SprtRainbw/spgd_faq.htm

So What is a Guardian Angel?
http://www.cosmiclighthouse.com/oct08/articles/guardian_angel