Social anxiety: the habits that feel like they save you
Gripping the glass, over-preparing, rushing your sentences, having a drink first. Each safety behaviour feels like it got you through. Each stops you finding out you did not need it.

You have a set of tricks for getting through. Maybe you do not think of them as tricks; they are just what you do. You hold the glass with both hands so nobody sees it shake. You prepare three things to say before you walk in. You keep your coat on so you can leave quickly. You speak fast, to get it over with. You have a drink first, or two, so the edge comes off.
Each of these feels like it saved you. That is exactly the problem.
What a safety behaviour is
A safety behaviour is anything you do in a feared situation to stop the feared outcome from happening. In social anxiety the feared outcome is usually some version of being seen as anxious, boring, odd or not good enough, and the behaviours are the things you do to prevent that being noticed.
They work, in a narrow sense. You get through the evening. Nobody comments on your hands. And when you get home, the conclusion your mind draws is: that went all right, because I held the glass properly, because I had prepared, because I left early. The safety behaviour gets the credit.
What never gets tested is the other possibility: that it would have gone all right anyway. That your hands would not have been noticed. That the unprepared conversation would have been fine. Because you always use the behaviour, you never find out what happens without it, and so the fear it protects against never gets disproved.
How they make things worse
There is a second cost, beyond keeping the fear alive. Safety behaviours are often visible, and what is visible is not the anxiety but the strangeness of the behaviour. Someone who speaks very fast and avoids eye contact and leaves abruptly does come across as slightly odd, not because they are anxious but because of what they are doing to hide it. The behaviours produce a version of the thing they were meant to prevent.
They also eat attention. Monitoring the glass, the coat, the prepared lines, the exit, means only half of you is in the conversation. The other half is running the safety operation. That is why social situations are so exhausting, and why you often cannot remember what was actually said.
The full list
When I map safety behaviours with someone, the list is nearly always longer than they expected. The obvious ones come first: the drink, the rehearsing. Then the subtler ones: keeping questions ready so you never have to talk about yourself, agreeing with everything, laughing a beat early, choosing the seat by the wall, never being the one to end a conversation. Some people have twenty or thirty. Each one is a small piece of evidence that has never been gathered.
Dropping them, one at a time
This is the centre of the CBT I do for social anxiety, and most people picture something humiliating when they hear it. Every experiment is designed together first. You agree to each one in advance, and we begin at a level you can already manage, because we are collecting information rather than testing how much you can stand.
An experiment looks like this. Pick one behaviour. Go into a real situation and do not use it. Hold the glass with one hand. Walk into the room with nothing prepared. Take the coat off. Then notice what actually happened. Did anyone react? Did the feared thing occur? Usually the answer is no, and that answer is worth more than reassurance, because you gathered it yourself in a real room.
Then the next behaviour, and the next. Each one dropped is a piece of the fear disproved.
About the drink
If you have relied on alcohol to get through social events, please say so. It is common, and it is worth being honest about. We treat it as one of the safety behaviours, and probably the most important one to work on, because it prevents you from ever discovering that you can manage a room sober. I will also tell you plainly if I think you need specialist alcohol support alongside the therapy.
What you keep
This treatment does not require you to become extroverted. Plenty of people finish it still preferring small gatherings to large ones and still needing quiet afterwards. What changes is that you can walk into the room with nothing prepared and one hand on the glass, and find out that the evening goes much as it would have done anyway.
If you recognise the two-handed glass and the coat that stays on, there is more on how I treat social anxiety, and mapping the behaviours is one of the first things we do.