We have had an extensive discourse on this smile or not to smile thread a few months ago in which I disagreed with the resident body language expert I wont re-open this can of worms.
Smirking is great I usually suggest AFCs stay away from smiling as much as possible because it will just encourage them to fall right back into their supplicating/nice guy AFC frame. As always experienced guys can do whatever the fuck they want. In Cajuns case he could smile or not smile and still be a monster PUA.
Yeah sorry about that, I just feel strongly that smiling is a huge asset. The thing that needs to be taken into consideration is whether there is attraction or not. At some point smiling can be a weakness and at others a strength. When the attraction starts and seduction begins smirking is a far better at this point in the interaction.
When you are just starting to talk a smile is fine, when your bodies start turning toward each other (Perper's second phase) smiling should be cut back and smirking or dead pan is more effective for building sexual tension. One thing you need to take into consideration is her response curve, how much sexual tension can you build before she walks away? Some women can't handle a ton of sexual tension, so you have to break it with smiles. You make the tension longer and longer before smiling, then the smile disappears.
In reality it doesn't matter whether your a smiler or not, your behavior has to be congruent with you. If you are a joker, then smile, if you are consistently serious, and smirk here and there I suggest maintaining that behavior. Whether you smile or not doesn't change whether you get the girl, it's up to you to know when to escalate your behaviors and eliminate comfort and move to tension.
Your body language surrounding the smile(including eye contact is the biggest strength of confidence). Smiling doesn't make you look less confident, its your body language surrounding it that makes you appear confident or not. How you hold your head, shoulders, arms, stance, move, eye contact, all contribute more to illustrating your confidence then a smile.