I'm not from LSU, but I'll try to answer some of your questions.
My first word of advice is to start now. Get to know women in the 4 sororities you're most interested in. Get to know women in the other sororities too - you might be surprised.
Find out which sororities did not meet quota this past fall and which sororities are not at total. The Office of Greek Affairs should have this information. A sorority that met quota and is at or over total cannot hold COB rush.
If a sorority is close to total/quota, and therefore can only extend a few bids, members of that sorority will probably approach only women they already know, to let them know about their COB rush. They won't do a big ad campaign just to fill three spots. This is one reason you have to get to know the sisters - they won't invite you to rush if they don't know who you are. If a sorority is well under total/quota, you'll have an easier time finding out about their rush.
And if things don't work out this spring, keep in touch with the sisters you've gotten to know. You may be stuck going through fall recruitment, but this time people will know who you are!
Good luck.
