I was a bit hesitant in writing this thread because flirting is not supposed to be a legitimate NT forte, but I guess it's ok to make a discussion about this once in a while just for kicks.
Anyway, do you think we INTPs (or NTs in general) are really weak at this, or it's just that we're too affected by the conventional notion that we're not good at this, hence we already give up on the endeavor even before we try doing it?
I've asked only one woman about my proficiency in this, and I felt that she's the among the few I know who's capable of giving a good estimate because she's a flirtatious pretty woman herself (talking to fellow NTs about measuring flirting skills would sound silly anyway) and she said...
"You're good actually. Not as good as ____________, but for someone who thinks that he's not really good at, you sure do know quite a number of things. I've encountered some guys who botch up their flirtation with me and they don't even know it."
I don't know if I'd take the statement as a compliment because the person she mentioned is the biggest playboy in our group.
Anyway, here are my thoughts on how an INTP can work this out:
1. The need to understand everything (Ti) would sometimes translate to the need of explaining everything (could be an Ne function), in detail. In my personal observation, I'm more eloquent than most NTs I know (most of whom are INTJ's I think, but I don't know that many INTPs to compare myself with).
2. The P function is the listening function. We're less likely to put a woman in a box of ideology than, let's say, the J's.
3. The Ne function (a very important one) is the gateway to the subconscious--the explorer of the various angles of the situation. though INTPs would like to always bind everything with the Ti function, stating the other angles of the situation can help us be in touch with our sentiments (as the Ti always seems to diffuse feelings). Unlike the J function who always needs to show that it is right, the P function stays in touch with everything, including feelings. Sentiments need to be expressed.
4. The eloquence of the Ne (by the way, my Ne is not that far behind my Ti. I think the very introverted INTPs have too much overwhelming Ti) in explaining the subconscious (which houses the person's feelings), plus the fact that the Ti will prevent things from being too sugarcoated (unlike the way INFPs do it) will give the INTP a very intelligent, sincere way of expressing his feelings, which can be a very powerful entity if developed properly.
5. Still, all women that I know hate the Ti function (unless one comes to you and asks you to solve her issues. Otherwise, all women I know hate it). The more technical things get (borderline Te), The more they seem to hate it, and it can be a waste of Ne/Ti cognitive processes if they'll focus on the technical issues.
6. If the Ti is too strong for an INTP to say things explicitly and the Ne doesn't show too much of an assistance, the P function can help the INTP dude in structuring his statement in such a way that it would be open-ended and figurative in its form, and can be taken in a romanticized context.
7. Of course, all the things I listed are just startups. Follow-ups are a different issue, which I think I still suck at, big time. LOL!