Everyone has this type of shakes. It is the result of your brain overloading your nervous system. you don't realise this because it is a subconcious thing and is a result of stress and tension. You don't realise it but conciously you recognise that this is a very small and quite often vital area that has to be done right the first time. This has a knock on effect subconciously and causes like a mini riot between nerves and muscles. All the stress and movement messages come streaming down so fast with the messages stay still! tiny movements! stop flexing.... It's like the internet melting down when playboy of the month does a live interview on youtube in the pink and crinklies!
You can minimise this with several techniques including slow deep breathing to calm yourself.
Just let your mind go blank and empty. Try a measure of Whiskey or other DARK spirit. That kind of alcohol will slow your mind down and calm you a little bit. Don't overdo it though or else it will have a negative effect. Just half a standard measure will be fine. Drink it neat and in little sips and give it an hour to get into your system.
Use a magnyfying lamp. this can fool your stressed out brain that things are larger and easier.
When dealing with small painting jobs, limit your time at the bench to just that bit and then walk away for an hour or so. don't try and do it all at once.... it's a stress releving excersise!
ON the other hand.... if you are on a roll and it becomes easy then just keep going.
Put some classical music on in the background. Particulaly Mozart. It is a good and calm distraction.
I have hand shake. some days it is worse than others and it is due to side effects of my heart medication that is keeping me out of a wooden Jaffa box and away from a BBQ!
Some deep breathing and slow release, a sip or two of whiskey and some Mozart on and I am off!
Boiling it down. you are just overthinking this and what you are attempting to do. cut that out, have a drink, some background music and crack on!