From birth to death, there is attached to every incarnating soul, a spiritual being who is in effect a guardian angel. This would be a soul that has some form of affinity with a unity of interest.
All guidance streams from the Collective Spirit. Ambassadors from the hierarchy and other enlightened beings, who are essentially kindred souls, sometimes attach themselves to incarnating souls prior to birth in this world. Sometimes there is agreement as to the voluntary task that is to be performed. They do not leave, and their task is as quoted in the Bible "He shall give his angels charge concerning thee." These are the Angels of light who surround their charges, whose self-imposed task is to guard, to guide, to sustain them and always to point the way to the spiritual path that ultimately leads to mastery. It is not an easy path; it is strewn with rocks and boulders. It becomes increasingly difficult as familiar landmarks have to be left behind. But as correspondingly low as you sink, so you can rise, and the heights to which you aspire are infinite.
The closeness of association between a person and their guardian angel is dependent upon the spiritual growth of the individual. Without any conscious co-operation there is only an unconscious help, spiritually directed, hoping to make an impact.
(See also Guides)
Books: Opening to Channel by Sanaya Roman and Duane Packer, provides advice and exercises for making contact with one's guide(s) as well as determining their form of communication and presence.