Hello my sisters in Greekness,
I have to agree with those who said talk to a variety of people in different organizations keeping in mind that discretion is always a great thing to practice. All of our NPHC orgs' founders made great strides and sacrifices for our respective orgs. I have heard of people in various orgs basing their decision on superficial reasons such as calls, colors or even what various friends/relatives have chosen. Making a lifetime decision based on these foolish things is sad at the least, and disrespectful at the most
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Another piece of advise would be to support as many greek-lettered functions as possible so that you can REALLY see how the members of the organization work together. Remember each of the "divine nine" are on different paths to the same positive destination--the betterment of our community. Therefore, when you support one, you support all.
Hope this helps.