One consideration is the level of care required. Dogs tend to be some of the friendliest and most loving animals, but they need a great deal of care and attention. On the other hand, you can take care of a goldfish in a bowl in a couple of minutes, but it will not cuddle up with you. Make sure you have the house and yard space you need for the kind and size of pet you choose. Another consideration is cost.
Pets can be costly, especially people on a fixed income.
When you are ready to pick out your pet, consider checking with your local animal shelter. Also plan for the costs of immunizations, vet bills, neutering or spaying, and food. The animal shelter or pet store should be able to give you an idea what these costs will be for your pet. Many people who are allergic to dogs or cats find that they are not allergic to animals like hamsters or chinchillas. Most people find that there is some kind of pet that they enjoy and can afford.