does anyone have any informal recruitment advice?

With an attitude like that you will definitely join a house this semester. Ignore what the other person said. Just be yourself and show a lot of interest in the houses that you like. Really get to know the girls that are recruiting you, because informal is a very unique opportunity where you're spared the fakeness of formal recruitment. Aphi and DZ do spring recruitment because they have a lot of girls from their house drop and they need to fill their quota back up. Other houses do it because some girls graduate early and they need to fill their quota back up.

Also go to a place where you feel valued. Hundreds of girls show up to APhi in order to get chosen for 4 spots. It can get very intimidating. After a semester you should have been able to observe some of the houses out and about. Don't take what people on this website say seriously. That's why "going in with an open mind," as cliche as it is, is always the best thing to do.

Alpha Phi usually does COB, but not this spring. I don't know about other houses but the reason Alpha Phi does COB is because it's highly encouraged by their excutive office not because girls drop.
If you are rushing in the spring and do not get a bid, chances are you won't get a bid during formal recruitment in the fall for several reasons:
1. More competition for top houses
2. Top houses take very few sophomores