You should just aim to look classy. Dress comfortably but still dress to impress.
Tank top: Only if it's a really nice one paired with dressier bottoms, not the kind of tank top you would throw on for the beach.
Anything that is a definite no: You know how you go out with your girlfriends sometimes and you see girls wearing these ludicrous outfits that are soooo skimpy and all you can do is turn to your friends and say, "What was she thinking?!" Yeah, just use your better judgement. Nothing that would embarass your mother.
Open-toed shoes: As long as they're dressy. Bring flip-flops to wear between parties so you don't have to limp into each house. (But don't forget to put the good albeit painful shoes back on before the party!)
You don't have to necessarily dress like a schoolmarm, though, to look like a lady. You can still be trendy and cute without showing a lot of skin or wearing too-small clothes.
Our recruitment chair drilled into us that "We're trying to impress ladies, not boys."
Other than that, remember that a genuine smile and a sparkling personality make every outfit perfect!
Please start a thread when you start recruitment. We're all so excited about this!
Love, Dyan
ps: Where are you rushing?