Okay so not a girl but here's the scoop: on average, it will be your job as the dude to keep things moving forward. This girl did you a huge favour by indicating she wanted more, and it's a hint you need to take.
The answer to "how touchy" is not finite. You touch until she backs down or until you don't want to go any further.
This is done primarily by feeling your way through the dark carefully, telegraphing your intent, and giving her the chance to slow you down or stop you.
So, for example, you're making out. You want to touch her ass. Put your hands on her waist and linger there, run them slowly across her body and head towards her ass cheeks. It should take you 3-5 seconds to get between waist and ass so she has enough warning to stop you.
You want to feel her tits. Start at the waist again, lift her shirt slightly as you slide your hand up her body towards the tits, pause before you touch them properly, casually stroking a thumb across the underboob before going the whole 9 years.
You want her to take her pants/shirt/socks off. Begin to fiddle with her pants or shirt hem around the waist. If shirt, lift slowly and gently. She'll either lean back and put her arms up so you can take it off or she'll stop you. Same goes for pants. Put your hands on her waist, use your fingers to make gently explorations into the waistband, then begin to fiddle with whatever button or ties or zip is holding them on, if she doesn't object, unbutton/zip/tie. Slide your hands around a bit more, explore further, gently begin to pull her pants down (leaving the underwear in tact).
It goes on like that, escalating until you're ready to stop or she is.