Do I have time to look after it?
This is a big one. If you don't have time to look after your pet - i.e. walk your dog, groom your cat or clean your rabbit's hutch regularly - should you really get one at all? Research what's involved in looking after the particular pet you want to buy and think about how you'll fit those tasks into you and your family's/flatmates' regular routine. If you work a nine-to-five job, it's also worth thinking twice before getting a pet that needs constant attention.
Can I afford it?
There are all sorts of hidden costs. First there are start-up costs (such as buying all the equipment, food and grooming tools required for your pet), then ongoing costs continuing throughout your pet's life (like regular vet visits, ad-hoc/emergency vet services, grooming products, food and toys). Research the average cost of all of the above and draw up a mock budget per year or month to see whether you can afford to look after the pet you want.
Does my home suit the pet I want?
Not all pets require a big backyard but if they do (i.e. if they're a big dog that needs more exercise than the average dog) it can be non-negotiable. Luckily, however, there are all kinds of pets that suit many different environments. Greyhounds, for example - who sleep long hours every day - can happily be kept in apartments as long as there's sufficient airflow, light and somewhere comfy for them to sleep.
Am I allergic?
Trust us, you're going to want to know if you're allergic to any animals before you take the plunge and buy one - just ask anyone who's allergic to cats. Test the waters by visiting a shelter or a friend who has the kind of pet you want to buy or foster a pet for a few weeks to figure out if you're cut out for your new living situation.
Is this an ethical sale?
'Puppy farms' might sound like cute and magical places but the reality is that they can often be cruel and highly unethical places with horrendous living conditions no animal should have to endure. Why not make your first stop your local animal shelter or RSPCA? These animals need your love more than most. Who knows - you might find your new (furry) soulmate.