The emphasis of playing the "insecure nice guy" I think is the fulcrum of this whole technique. You're covertly annihilating a relationship (a massive social nuke). when you go in as a nice guy, she let's her guard down and actually considers what you have to say. This is the epitome of "wolf in sheep's clothing". If she gets an inkling of hidden agenda, her guard will go up and the subtlety won't work and this entire technique is based on subtlety. Therefore, because of the crucial necessity of appearing insecure nice, I think dressing different, having nice guy props (glasses, pocketprotector, what the hell is a niceguy prop? wool sweater? haha!) anything that could make your "nice guy" persona more convincing is in your favor.