Car parking spaces on supermarket car parks seem so small. Especially when you drive anything bigger than a Peugeot 206. Getting in and out of these tight parking spaces can seem like a complete nightmare. Especially when the car park is particularly busy and you have someone waiting for you to come out so that they can pull-in.
The best way to prepare for these situations is to practice. When you go to a supermarket and it is quiet, practice your bay parking. Go to a part of the car park where it is quiet and imagine that you will be parking between two cars. Think about how you need to pull-in and how much space you need to leave on either side.
You should try reverse parking too. Some people find this easier. Again, practice makes perfect so keep trying.