If you have a neighbor you're on good terms with, you might wish to cooperate over your use of the land between you. For example, a neighbor with a particularly narrow or twisty driveway might be aided by driving over your land for a bit. Or perhaps your property has a public park behind it, and your neighbor would otherwise have to take a roundabout path to get there, and you're find with them walking through. The next question is, do you need to grant the neighbor an official "easement" or "license"? And if so, will you need an attorney's assistance?
The legal concepts of "licenses" and "easements" are frequently confused. Broadly speaking, an easement is a more serious property right; it is the legal right to use someone else's land for a particular purpose. Easements are often recorded at the county clerk's office and encumber your property's title. Easements are commonly granted to public utility companies, for example, for various power or plumbing lines.
While you do not need a lawyer to create or grant an easement to your neighbor, it can be a good idea to retain one. (Learn more about easements from Nolo's Overview.)
You might not want to take the step of granting an easement, however, when a simple, revocable license would suffice. A revocable license can be terminated by the licensor (in this case, you) at any time, with or without cause.
A license need not be in writing, but to protect you, it probably should be. Many unforeseen issues can arise in the granting of a revocable license. For starters, you want to make it clear that it can be revoked unilaterally at your discretion.
Also, if your neighbor moves, does the license pass to the next homeowner, whom you might not be so friendly with? If your neighbor stays, and (in the driveway example) her three children grow up to be obnoxious teenagers, each with his or her own car, are all of those drivers now permitted to drive over your land? What happens if one of them buys a noisy motorcycle instead of a quiet sedan? Surely, in each of these cases, you would want to have something in writing that limits your obligation to allow your neighbors to drive across your land.
An experienced attorney can help you think through issues like these, along with many others that you might not be able to imagine. The attorney can help ensure that your grant does not hurt your interests in the future. Given that the project involves only a few simple conversations and some basic document drafting, the cost of the legal fees would likely not be exorbitant. Indeed, if a dispute ever arose, these simple preventative steps could easily pay for themselves.