Actually, I convinced 3 to join this semester. Maybe if I give you an idea on their backgrounds it will give you an idea about how to recruit friends who you think would make great Alpha Phis.
Ashley - she's a freshman, but we've known each other since she was 14, and I showed her Florida Tech. She was pretty resistant at first because she is anything but the "stereotypical sorority girl"... she skydives, plays guitar, etc. She's a little crazy and goofy but I thought she would be a refreshing addition to our chapter. She's also very tomboy-ish, and I think what snagged her was the idea of having a group of girlfriends for the first time. Now she loves making t-shirts and hanging out with her new sisters.
Laura - she's my old roommate. She is President of a Greek service organization on campus and has become frustrated with how it's gone downhill... people only want to be social and don't want to do any philanthropy. She liked the idea of the comraderie that she had lost with her organization, and she already knew several of us, as well as living with 2 of us the year before.
Tamalyn - my current roommate. She was interested in Alpha Phi our freshman year but our chapter was having difficulties with the other sorority on campus and I didn't think it would be a wise idea to bring her to a meeting in that situation. A couple of girls convinced her to help them start a local sorority and she was very gung-ho about it, but nothing ever got done. Suddenly the girls got their stuff together and got it started, but left her out. She was really hurt and I offered her an invitation again to our informal rush events because I knew she would make a great Alpha Phi. She's very big on ritual (or rather, WILL BE, since she's not initiated yet

) and the spiritual aspect of a sorority, and she plans on being a very active alumni. She always felt she was in the shadow of the older girls who started the local and Alpha Phi gave her the opportunity to shine on her own.
Find an aspect of Alpha Phi that applies to something these women want or enjoy... whether it be philanthropy, comraderie, or something else... there's a lot more to being in a sorority than what most people see on the surface. See if you can invite them to a meeting or something so they can meet all the ladies. It's usually the best way to get someone to join by helping them make some new friends.