1. What age do you release them? Beware of breeders letting kittens go younger then 10-12 weeks old - most will not adopt out till 12-16 weeks old.
2. Ask what associations they are registered in (USA - CFA, TICA, ACFA) Not sure of the exact ones for overseas if you don't live in the US. Ask if they show their cats and what titles do they have. A good quality kitten (even if its pet quality) will have a lot of champions and GRAND champions in the background. If you don't see that on the pedigree, its usually cause the cats are not top quality and probably should not be bred.
3. Ask about shots, health guarentees. Ask if you get a copy of the pedigree AND registration papers. Most breeders will not give the registration papers till the kittens are spayed/neutered; however a lot of breeders will have had that done before you adopt - so the cost will reflect all that.
4. What kind of food are you feeding and litter are you using?
5. How many litters a year do you have - a breeder who has more then 2-3 litters, may be a backyard breeder. How often are the females bred?
Try to visit the breeder/cattery to see what kind of enviroment the cats live in - are they always caged in small cages, how does the breeder socialize the kittens? Are they exposed to children/other cats/dogs, etc.
If you don't get a positive feeling about things no matter how cute the kittens are or if you feel sorry for the "poor little kitten" DO NOT BUY FROM THIS BREEDER!