If you don't have a set of large grip cooking utensils you can purchase a roll of Rubbermaid shelf liner and cut it into strips and wrap around your cooking spoons, ladles and spatulas and secure with a rubber band. The tacky rubber surface will make it easier to grip and you can wrap it around until you build it up to make it a larger grip. This rubber shelf liner can also be used for many other helpful things. Cut squares of it to place under mixing bowls so they won't move when you are stirring. If you can still grip a jar lid but just don't have the strength to turn it then using a piece of this rubber material to ease your grip may just be the thing.
Some people find that they can grip bowls and things better if they are wearing rubber gloves.
A flexible cutting board really helps those that must use one hand. It also keeps us from having to use our hands to gather up items to place in a bowl. Just chop on the board, then bend to fit whatever container you need to place the food in. Use Plastic Mixing bowls rather than heavy Glass ones. Preferably ones with handles on the side.