Re: how to prevent knots in their fur
Welcome to CatForum.
The only way I know of to prevent knots is to frequently or regularly groom your kitty. Sometimes feeding a better/premium diet can help their coat immensely but for now there are some other things you can do.
First, do not try to cut the tangles out with scissors unless you have pushed a comb between the snarl and the skin. It is *very* easy to pull the cat's skin up in a 'tent' and get it in the path of the scissor blades if you do not have a comb in between to keep the skin away from the cutting edges.
Next, where are this cat's tangles? If they are behind the ears, along the shoulders, back and/or hips, then I think WE are the problem. When petting a long-hair cat, be sure to always pet in the direction of hair growth and do NOT swirl your fingers through the hair in a circular motion. If you like to scrubble (a sort of finger-massage) be sure to sort of scrubble-comb your fingers through the hair to prevent it getting tangled.
Finally, many long haired cats get snarls and tangles behind their elbows and on the seat of their 'pants' along the back of their legs. Some also have trouble with poo/pee clumping and tangling hair 'back-there' and require a "potty-patch" shaved around their mustn't-touch-it to help them stay clean.
Anyhow, I hope you've found these suggestions helpful.