I don’t mean to insinuate that you’re doing so, but looking at them primarily as resources and potential helpmeets instead of as individuals is not a good way to go about it, in my opinion. Not only does it unnecessarily de-emphasize their agency (scowlyface), but it also smacks of exchange and contracts, which should both be avoided like the godsdamned plague unless (until?) you really know your stuff. Either way, not a great plan. That’s why I emphasize the pursuit itself as the reward, not what you might gain from the People themselves. 

The few rules and generalizations about them that exist– and there are but few– rely fundamentally on caution with the changeability of their nature, and how different they are from us.

It is therefore my argument that you base your decision to begin on whether or not you want to attempt to work with them. Start there, with research and the aforementioned pursuit, and see if it seems like a path that you’d like to try. If you should meet one, take them as individuals instead of a collective, and decide on a case-by-case basis. In this circumstance, divination would indeed be more helpful. It would then help you understand their intentions, see past any potential trickery, and judge whether or not to pursue some sort of relationship, if they wish to interact with you. In that way, it’s like any other friendship, if one of those friends can curdle milk, occasionally steals children, and dyes their clothing in blood for funsies.

Narrowing things down would also be helpful. Do you mean to travel to the other side to interact with them there? Or will you instead search for those that either live in, or regularly visit, our plane? Or, you know, all of the above? These distinctions can determine how you begin, but there’s a lot more besides. (Especially if, yes, you mean them to enter your home! My brownie friends don’t live in my house right now, specifically because I’m so messy. They stayed for a week and stole six cards from my then-favorite tarot deck as protest until we negotiated a truce. They live in the shrubbery [Ni! Ni!] and on our porches for now. Did I get those cards back? No.)

They are innumerable and, in my own belief, more varied than we could ever adequately categorize. Yet lore and experienced wonderlings can give us a wealth of information on types, tendencies, and individuals.

For lore, you can’t go wrong with sacred-texts. Admittedly, this hits more on the British Isles side of things, but I’ve found the works of William Butler Yeats and several from the Celtic index to be both enchanting and helpful. I’m also totally loving Andrew Lang’s fairy books. Fairy tales, man. They are where it’s at.

As soon as I gather good resources for non-Irish/English/Welsh/etc resources, I’ll add them. My bookmarks are sadly lacking. Bad Lily.

As far as experienced wonderlings are concerned, every mod at modernguidetothefairfolk is well-versed and wise, to start with. Check out this post and its successor from gardenofthequeen to get at more details on how to begin, along with wonderful links on how she categorizes fae. See also spiritscraft‘s wonderfully succinct answer on astral travel, and duskenpath‘s blogspot on the same.

Additionally, I’ve learned a lot just from reading what other people write and collect about their experiences, here and Elsewhere. I could start naming the people who’ve penned beautiful and illuminating accounts of their experiences, but then we would be here even longer than we have been. (I’d do it, though. Oh, I would. You’re aaaaall wonderful. Deal with it.) But seriously, it’s like a new realm of lore is being written by all of us.

So, there you go, far longer than it should have been. I really do hope this helps. Looks like my origin story is going to have to be its own post. Schwups.

TL;DR: Research, research, research, protect yourself, seek some out, and see what you may find while continuing to protect yourself.