As with what everyone else said...here is a recap, please consider this carefully as I am thinking that a draft may not be right for you, that a light horse is. A draft isn't for the faint of heart and as they age, they have medical issues and don't live as long.
*You will need a strong heavy duty fence, they will and do lean on them. Hot wire along the top is advisable. Each of our poles the board was attached to is sunk in concrete for a reason. They will STILL break boards by leaning on them, scratching, or a well placed kick.
*Blankets are harder to find if you need one. When you get a blanket for a draft you really need to be spot on with your measurements as if it is an inch too short it will rub and they do become annoyed/irritated.
*They can be ridden but depending on the side of the draft, do take longer to cool down. They are not the fastest moving animal in the group, can take longer to mature and their joints to fuse and mature as well, it is strongly suggested to get x-rays of their knees to ensure proper growth and health.
*A draft does metabolize anesthesia a lot differently than a light horse and it has been shown in some that less is better to sedate them for minor things. They can be stubborn, do not like to be roughly treated or trained. Many are quick to learn.
*Their tack costs a lot more and you cannot scrimp on their equipment. It takes some doing to get a good fitting saddle, a good harness, or anything else for them.
*Many farriers will refuse to shoe a draft or will not do them unless they have impeccable manners or you have a shoeing stock. Call the farrier you intend to use and ask if he will do a draft and if he has knowledge of their hooves. My own farrier, who does shoe and trim drafts, has different set of rasps, clippers, clamps, shoes, and nails he has with him, they do cost more often times as well. Right now, I pay $95 to get front shoes on and the hind hooves trimmed.
*It is advisable that the stalls be bigger in case you have to put them in. They, like any other horse, like a bit of space to move, lay down and stretch out.
*Feed wise, we leave round bales out all the time, they will go through one in about a week or so. Again, as they age, it may be a bit harder to keep weight on them, depends on their background, what was done to them, their breed, and what you intend to do with them. Both my Percheron mares are on senior feed now for various reasons. Shots are the same price wise as a light horse, as is basic care. Hay we feed good orchard grass, field grass, a bit of clover, and they do fine.
*A draft loves to have a job and a purpose and they will excel if they trust their owner. Once you win their trust there isn't anything they won't do for you. Just because they are big doesn't mean they are dumb and sometimes trainers forget that.
*Hooves are a BIG thing with the drafts....many breeders are not breeding for soundness, but for height and you have to look at their whole conformation. Are their hooves in good order? Bone, is it nice and thick, good density, a nice straight back? How do they stand? Are they sway back or cow hocked? Teeth? Is there an over or under bite? If you have a bad hoof I can tell you from personal experience you will be battling that for the entirety of their life.
*If you can lease a draft before you own one so you know what your getting into. I have seen too many people get a draft, only to realize they are just too big, too much to handle/ride/work with and they either get thrown out into the pasture or sold from person to person to person.