Im mostly writing this for myself to come back and read when i need to, so keep that in mind.

I would say look at both pick up ad ltr as game of 5 card poker.

Pick up is when you are sitting across the table from each other, all 5 cards faced down, and you are bluffing, and being sly, and making remarks and taunting.

You should think of Ltr game should be playing 5 card poker, but sitting next to each other, and showing her 2 of your cards. As the game goes on longer and longer (the relationship progresses), you show her 3 of your cards. As the game keeps on going you show her more cards. Occasionally, on one or two hands, you switch it up and dont show her any and bluff. Then you show her some cards again after that hand. EVENTUALLY, (waaaaaay into the relationship) you show all of your cards, but occasionally hide some to keep things interesting. Never show all your cards in the beggining, always have some hidden.

I hope you guys understand this analogy well. Comment if you dont and i will clarify.