When are good situations and/or ways to flirtatiously touch a woman without seeming weird or out if place?

For some context: I’ve been on a few dates with women that I thought went very well only for them to tell me later that they got more of a “friend vibe” from me. While this can certainly be for a number of different reasons, after looking into it a bit myself, I found that a big reason could be because I wasn’t flirtatious enough. I always thought I was pretty flirtatious but I looked into that more and it seems like one of the biggest ways to flirt and/or build more of a connection is through touch (obviously not in a disrespectful way). I don’t want to make it obvious that I’m trying to touch them more often or make the touches seem weird or out of place. So what are some situations and/or ways I can touch without seeming that way? I know the basics like if you open a door for her you can guide her a bit with your hand lightly on the small of her back or something but what are some other ways that would create a flirty vibe more than a friendly one. I know this may seem like a silly or dumb question so sorry in advance.