Originally Posted by Lola the GSD
It always starts out she's licking someone's hand
This is when you need to take steps, since you know where the licking is going to lead. And the steps should not include swatting; being hit is exactly why she is becoming more aggressive. Holding her at the scruff till she "calms down" is also making her more aggressive. In short, these actions are scaring her and making her think she has to protect herself from you. As she gets bigger/older, this behavior will get worse unless you stop instigating these physical confrontations.
Licking can be an appeasement behavior, so my guess is that she wants to play, doesn't realize that her nipping isn't wanted so she offers "appeasement" and when that's accepted, she moves on to play. It's probably rather surprising and scary to her when she gets yelled at/swatted.
So, when she begins licking your hand (or anyone's) she should be distracted with a toy, or something she is allowed to chew. If, at any time, her teeth even barely touch your skin, all interaction with her should stop dead for a minute or two. You can walk away from her, turn your back on her, completely ignore her. After a minute or three, resume contact; if her teeth touch your skin, ignore again. Don't say anything, don't scold, don't try to push her away, just silence and ignore. You want her to learn that teeth-on-skin = no play, no petting, no attention. It may take 100 or more repetitions for her to get it.
This will take some time, possibly a few weeks, so don't give up after a few days.
Because your dog is a little older and she seems to have reacted pretty strongly to your physical corrections and scolding, you may want to also get a positive-trainer/behaviorist in to assess her and to show you exactly how to handle this situation and how to avoid more problems down the road.