Two places I go to dont have plastic bags they just have clear ones which are good too.
The following tips may work
Always make a habit of keeping one or more bags in your car.
during seasons when coat is necessary,this is an ideal place to keep your reusable bags,grab your jacket ,and grab the bags.
Always keep some bags by the entrance door you use most frequently.
you can use the bags that fold and roll like a ball and fit conveniently in your purse so you can use when needed.