Inasmuch as enemas serve a variety of functions, I suppose that one must consider the intended outcome.
In a solo or self administered scenario, the enema is usually the foreplay and the preparation may well enhance the process. The anal/prostate stimulation certainly moves us guys toward the ultimate outcum.
If one has an enthusiastic partner, various scenarios seem to enhance the enema experience. Some like the punishment aspect and may include some type of correction such as scolding, spanking, corner time, etc. Some prefer the inclusion of a degree of dominance or submissiveness. The role play may well be the foreplay.
I happen to prefer a couple of more tame, but sensual nonetheless, role play scenarios. They may lean a bit toward some MedFet situations. The foreplay may well include some more traditional types of activities to get both warmed up a bit.
I enjoy playing the role of a doctor or therapist who may inquire as to the circumstances that brought the client/patient to me. In this interview, I may suggest some therapeutic procedures to further evaluate symptoms and appropriate treatments. Discussing these treatments and asking about experiences often begins to get the juices flowing and setting a mood. Preparation can be good foreplay. I might examine a variety of areas and manipulate various erogenous zones in an effort to enhance the stimulation.
It is my experience that enemas are far more enjoyable if one is already buzzing and there is a level of stimulation. This is especially true for anal penetration. Thermometers, fingers, speculums, or other anal toys, may well be enjoyable.
A shared bath, perhaps with bubbles, or a massage are certainly wonderful ways to enhance the mood. Whether the enema is the ultimate sexual act, or whether masturbation, oral, or intercourse finishes off the interlude are certainly desirable outcums. The beauty is that there isn't just one way to assure a happy ending to this simple procedure and pleasure.