Of the many exotic animals available as pets, ravens are certainly not ones that should be taken without considering all the facts. From personal experience, I can advise you that they are not just a pet; they are a personal investment.
Ravens are highly intelligent, clever, and mischievous creatures, and those qualities should be treated with respect. It would be foolish for them to be immediately obedient and loyal like dogs, or aloof and self-sustaining like a cat. Ravens need interaction with their owner, and they need plenty of toys and mental stimulation. Having a raven is very much like having a child.
Consider the space requirements. Ravens are active birds, and some species grow quite large. Unless you are willing to take them out for daily exercise, then you need to provide them with a large cage, one with enough room for them to flap around without damaging their wings. You also need to provide them with plenty of perches and a place to roost, along with something to bathe in. It's best if you can keep the cage away from walls, because they will play with and destroy anything they can get their beaks on, including your drywall.
Understand that with their omnivorous diet, they can make quite a mess. Ravens also have an instinct to hide their food, and will take the remains of their meals under their cage lining, inside toys, and in every available nook and cranny. Owning a raven would drive a fastidious person insane, as ravens can make a mess almost as soon as you clean it. Constant cage cleanings are necessary, as leftover food and bird waste can swiftly combine into an overwhelming smell.
Ravens need almost constant stimulation and companionship. They are social creatures, and love to play with their companions. In a home situation, they will even play with the pet cat. Their mischievous demeanor also encourages them to test their bounds, playing with the forbidden simply to get a reaction from their owner. Owning a trio myself, I cannot comprehend owning a single bird, unless you were able to be with them for the majority of the day.
Their intelligence is on par with a toddler, and that actually makes it easier to provide them with mental stimulation. Small, bright and shiny toys are perfect for them. Toys designed for parakeets and cockatiels are ideal, as they are usually made of acrylic, have bright colors and little mirrors and bells, and they are about the right size for a raven to play with. Ravens also enjoy the types of toys one would give a toddler, such as playpen activity centers, shapes and blocks, or anything else light and colorful. Almost anything will work as a toy for ravens, including aluminum foil balls, jacks, soda bottles, and even empty vegetable cans. Almost anything they can manipulate and hide will become a toy for them. Never forget their need to hide items, and provide them with a variety of containers.
Being omnivores, it is almost easier to provide food than to provide toys. Ravens will eat almost anything presented to them, though they will let their owner know when they don't like a food. Like children, they are fond of sweet things, and enjoy getting treats. Maintaining a balanced diet is important, as well as providing vitamins to supplement what they might not obtain through their food. A high-grade cat food (the kind with lots of protein) and canned fruits and vegetables are an easy staple for the bird, with raw meat and animal by-products as a meal highlight. Oatmeal and potato flakes become filler in most meals, and even small bites of bread will keep a raven happy. Offer them favorite foods, and never forget to mix multivitamins in their meals. Ravens can become bored with the same food every day, so learn to read their desires, and mix up what you offer them. My murder even likes cat treats for when they're getting spoiled.
Owning a raven is very much like having a child in the house. It is so much like that, it doesn't even really feel like owning the bird, so much as having a companion. Only if you are capable of meeting the challenge a raven poses to you should you get one as a pet.