Well, re: picking letters, two things you really have to take into consideration.
1) is the name used by another group? Check
The Greek Info Pages And
Local Sororities . Also run a general google search. This will help you narrow down your choices. Avoid using the same letters as another group, it just causes confusion. Keep in mind the different combos you can have (2 letters, 3 letters, 4 letters are the most common)
2) What are the core beliefs of your group? Why are you a group? What makes you different? what personifies you? These are usually what groups base their letters around, core beliefs, values, or things of ritual importance. Example: my letters, Tau Delta, derived from the original club name of Tomo Dachi, which was necessary because Greek Life was banned. The taking of greek letters was a huge event in our sorority, but we wanted to honor the Tomo Dachi roots, so there ya go.
Good luck, stick to it, and don't let negativity get you down. Starting a new club, any sort of club, is difficult, but with sisters at your side, anything is possible!!
Local love,
Tracey