I go through packets and packets of #7s. They're artifically natrual, if you know what I mean - lots of length and you know that someone is wearing falsies, but they're softer than a set of big batwings.
I agree on the #7's...
but for myself - and I feel bad b/c even though I've got the great MMA discount I'm still *seriously* cheap - I get #4's and cut them into thirds - then use them as half-lashes just on the outer edge. They blend nicely, aren't as long as the half lashes and... hello? three pairs for the price of one!