(Uttering the mantra..."Discretion is Key...") 
My experience was a bit different than others, since I didn't become a member of an NPHC organization until a year after I graduated from college. The alumni/alumnae process is different than the collegiate experience, and I won't go into detail about "grad chapter" induction.
However, I did watch a few friends and family members go through the process from a close enough distance to say that the processes differ. Most NPHCers will say that we don't recruit. On the surface, that's true. We don't do recruitment in the way that you do it.
What happened at my alma mater (and at my niece's alma mater) is that all of the NPHC organizations had a one-day "interest meeting" where representatives of the groups stood up before the assembled guests (men and women) and gave a brief lesson on the history, philanthropies/foundations, and programmatic thrusts of each organization. After these meetings were over, NPHC groups
on my campus would hold separate "teas" or "smokers" at some point during the fall or spring semesters. We don't seem to have the exhaustive round of parties and socials that NPC organizations have; my
theory is that since NPHC organizations are primarily service organizations, they wish to downplay the social aspect.
While there was nothing keeping you from visiting each group's individual interest meeting, it didn't usually happen since a lot of people, from what I have seen, have a good idea of which organization they want to belong to before they get to this point, and they direct their energies toward that one group.
Each of the NPHC organizations has their own rules on how they handle "Membership Intake", so while the processes share some similarities, overall, the process differs from group to group. One thing that is different is that it seems that NPC organizations have a much longer "Pledge" or "New Member" period than we do. Again, this varies, and I don't intend to speak for all organizations, but I'm amazed that NPC organizations' New Member periods can spread out over an entire semester.
Another key difference is that freshmen/freshwomen are not usually eligible for NPHC Membership Intake unless they have completed a certain number of credit hours. Generally, new members are sophomores and juniors, there are even seniors in some new member classes. Occassionally you'll encounter a member of an NPHC group that was inducted as a freshman, but it's usually after their third quarter/second semester.
DISCLAIMER: The above statements are taken from my own personal experience and are not to be taken as a rule of law..
That's what is called a CYA statement.
