Practice while riding on your own. You need to be able to drink while on hard or long rides with others and doing a wobble, contacting someone else's tire and causing a crash will make you very unpopular.
I like to be in the drops when I have to take a hand off in sketchy situations. I place my index finger firmly on the side of the brake lever. (But!! Don't do this with Shimano brifters! You don't want to be shifting! I'll never ride Shimano brifters for exactly that reason. I was doing this before brifters were invented.) Basically, just ride and practice. (But don't do anything with others until you can do it and hold a straight line. You have no right to crash others. Do the practice. You'll get this. And in time, you'll be hoping the newbies listen to someone like me to save your skin.)
I know this sounds harsh. We've all been there. Welcome to road cycling! Stick around!
Ben