Make sure you've figured out the size of your character in relation to the jar. When shooting your greenscreen footage, give your actor an on-set marking to make sure they are not stepping outside the jar's space. That keeps things consistent for you when you go to composite.
I would also recommend doing some sort of practical effect for any close-ups of the actor, to help simulate the distortion of the glass. If it were me, I might try to shoot those closeups with a thick glass partition, so you don't have to add that effect in post. If I were doing this on a scrappy budget, I might go someplace with big revolving doors, and use the curved glass panel as a stand-in for the jar, with a portable greenscreen in the background.
Pay really close attention to perspective and depth of field, and if possible, shoot your background plates first so you can refer to them in your studio setup, where you have more control. A lighting diagram of your background set will help you match the lighting in-studio.