I just got my first horse and it was quite an experience. It’s great if you or your trainer knows the owner, but I know that’s not always possible. Make sure you get a good vet chech with x-rays and bloodwork, also have someone experienced with you and if you think something is wrong don’t go for it.
If something doesn't seem right pass on the horse. No matter how pretty or cute they are. It all depends on what you are doing with them too. My first horse I bought was a rescue I had adopted that I had hoped to turn and rehab into a lower level show horse. That however , did not happen as she was to lame to be even considered as any type of performance horse. Get a full ppe done, try to get any history you can on the horse in question & Make sure to look for gold confirmation and build and go for a test ride or maybe two or do a trial (some horses just do not click with certain people) most of all before buying make sure it is the right hose for you and what you are trying to achieve.
Always do a proper PPE including a blood test to test for drugs, can never be too careful, especially if you are spending a lot of money. I have seen it happen myself. Bring your trainer along and test ride the horse as well and evaluate both of you as a team