Excellent post RS.
Here is some information I have heard on the forum, and some of my own experiences, put together randomly. I am not sure if this is what you are interested in but it may be helpful
If you want to work with local spirits, it pays to research local traditions. If I went to Ireland I would research Irish mythology and the lore of local Irish spirits. I believe it is respectful and advantageous to approach local spirits in the manner they are accustomed to.
There seems to be a lot of debate regarding the classifications of spirits and entities. Charles Leland Leadbeater wrote a book called The Astral Plane, Its Scenery, Inhabitants, and Phenomena. This book was published 114 years ago during the Spiritualism revival (if I have my history correctly) and has interesting concepts on the classification of spirits. It can be downloaded free and legally here: http://darkbooks.org...hp?v=1791067929
Spirits who show up on your doorstep and are very eager to please you may not be good news. It is perhaps hubris to assume that you are such a great and powerful witch that strange spirits will bend over backwards to please you. If you encounter a spirit who is willing to agree to anything or submit to every test, you may find yourself with a pest trying to worm their way in.
If you are communicating with a spirit, and it tells you everything you want to hear, be aware. If you have always wanted a red dragon familiar, and all of the sudden your pendulum is telling you that a glorious red dragon has been watching over you your entire life and is now ready to grant you amazing magical gifts, consider that you are being lied to. Make notes when you communicate with unknown spirits, and be wary if they begin to change their answers if you express dissatisfaction with what you hear. This thread is an excellent example of someone who got very excited with spirit communication, and perhaps was not as alert as they should have been to red flags. (Notice that after the OP said he thought the spirit would be Biblical in nature, whatever he was communicating with changed its story to come in line with his expectations.)
It is egocentric to assume that every spirit you meet is interested in talking to you, is there to help you, cares about you, or is able to communicate with you at all. Not every spirit is a human in ghostly form; there are entities with which humans cannot directly communicate.
Spirits live everywhere. They live in our homes, gardens, buildings, towns, and wild places. Building homes for spirits to live is common amongst all cultures and may help foster good relations with the spirits in your life. In his book Protection and Reversal Magick, Jason Miller provides a ritual of offering to spirits. He says that humans, being often out of touch with the spirit world, can offend spirits in ways we do not notice or understand. Giving incense offerings (the energy of which the spirits may use to their advantage), he says, will appease spirits and encourage good will between you and the spirit world. There seems to be a lot of useful things a person can do to earn allies amongst nature spirits, the basis of which is acknowledging them and treating them with respect.
Some people advocate a test to see whether or not a strange spirit is "good" or "bad". In this test, you simply ignore the spirit for a few weeks. If it sticks around, it is good; if it leaves, it is bad. I do not believe that this is sound advice. A spirit of ill-intent may be perfectly willing to leave you alone and come back in a month when you are suddenly willing to trust it. Likewise, a spirit of good intent may roll its eyes at being ignored and leave to find someone else willing to accept their help. Instead of tests, try speaking to spirits as you would another person and getting to know them the old-fashioned way.
When wanting to foster a relationship with ancestors, a witch can hold Dumb Suppers. I don't know much about them personally, but it is a dinner with the dead. Sometimes they are just held on Halloween, but you can do it whenever you please. You cook and set out a proper dinner, with several place settings. You invite your beloved dead to eat with you, and talk to them like family.
When you present yourself to the otherworld as a witch interested in spirit contact, it is advisable to be ready for them when they come. Spirits do not follow our earthly schedule, and they may show up at the most inopportune times. Some members on this forum have designated certain areas of their homes as 'no spirit zones' so they can get some peace and quiet. If you are not used to spirit contact, a first encounter with one can be startling or even frightening. Don't freak out and command the spirit away (how rude to invite someone in and then slam the door in their face!). Just as spirits may show up whenever it suits them, most spirits are not our servants and may not show up whenever you call them. When working with a spirit, it may be advantageous to designate a certain day and time to meet weekly.
Spirits have their own stuff to do. They are probably not hanging around and watching you constantly.
Actions by spirits can be misinterpreted. What we see as malicious or aggressive could be a spirit acting out of curiosity or simply teasing. If there is a spirit acting in apparently malicious ways, it may be best to speak to them plainly instead of whipping out the banishment kit. Addressing a spirit and saying, "this is my home and I do not want you to do X any longer" can go a long way towards solving problems.
Speaking from the perspective of a novice, I find some spirits will test me, so to speak. They will cause problems for me and wait to see how I solve it. I believe my reactions to these problems are very important, including how much I let them bully me before I take a stand. In this manner, I have found paying attention to my life is extremely important with working with spirits, because sometimes they can act in subtle ways that may not be easy to immediately notice.
Also speaking as a novice, sometimes spirits will do stuff that will plain freak you out. Being home alone and having the television turn on by itself, or coming in to a room to find stuff moved around can be distinctly unsettling if you aren't used to it. This is just something you will have to get used to and overcome. Or you could ask them to stop, but what's the fun in that? Discomfort means you are overcoming your limitations.
Regarding Guardian/Guide spirits: It has been advised to me by some very experienced members on this forum that these spirits can be very forgiving. In the past, if you believe you have sent your guide away out of ignorance or fear, there may be a possibility that your guide is still waiting for you somewhere. Do not give up on the idea that you may meet up with them again; what is the worst that could happen if you try?
It has been suggested that reaching out to any random spirit is like reaching out to any random person on the sidewalk. They may end up being a great friend, or someone you hate, but more than likely they're just average people with little connection to you. Instead of reaching out to any spirit, focus on who you would like to attract: Ancestors (both in blood and spirit), benevolent beings who are interested in helping you, a spirit who has knowledge of something specific you want to learn, and so on.
Some spirits help us out of the kindness of their hearts. Other spirits help us because they want something in return. I have been advised on this forum to be very careful with a spirit that is willing to help without apparently getting anything back, especially if they are strange spirits with no connection to you. Working with a spirit who wants something in return is not necessarily bad, just make sure the contract is clear before you get started.
Some spirits do not take kindly to being ignored, especially if you have made a big show of communicating with them regularly and wanting to form a partnership with them. If you only talk to a friend when you need something or when it suits you, you would be called at best a fair-weather friend or at worst a user. "Out of sight, out of mind" isn't an excuse to neglect your relationship with spirits. If you can't commit to maintaining a relationship even when you're not 'feeling it', it may be best to stick with casual communication and avoid trying to earn Allies for now.
It is my opinion that being able to see and "feel" spirits is a psychic talent. Working to open your psychic awareness may be advantageous if you want to see spirits. Even if you can't see them, using a tool to communicate with them should be accessible to anyone. Pendulums and spirit boards are popular. I have used tarot to communicate before as well, but that is not as optimal for me. In the past, I have used a physical alert system so a spirit could attract my attention, which sounds fancy but I really just told the spirit to knock over a small tube of medicinal ointment if it needed to talk to me. There are many clever methods for allowing a spirit to get your attention, I believe wind chimes are popular. Just as you are able to call your Allies, I believe it is germane to give your Allies a way to call you if your psychic senses are not developed enough to 'hear' or 'feel' them.
Nature spirits are not always nice, loving, and all-forgiving. This post by Michele talks about her relationship with her Elder tree, and I think it is a wonderful description of how even trees will hold you to high standards.