Fact: Pound for pound the domestic cat is the most efficient/ skilled predator on the planet. They are used to being the smallest kid on the block and thus are prideful... and a little bit sensitive.
1.) The slow eyeblink: Y'know how a cat will make eye contact then slowly close their eyes and open them again? Translation: "We're cool/ I like you at the moment." They want you to do it back, in fact, if you're a pro, you can get them to stop being mad at you by initiating this type of communication.
2.) If a cat is wagging its tail, it is not happy. : Most people know this, but what they don't know is that 85% that means the cat is pissed, 10% they are playing a mind game with you (We'll get into THAT later.) and 5% They're bored. BUT when swishing the tail, they are NEVER happy.
3.) If a cat rubs its body/face/ tail against you it is the highest compliment ever. That means the cat wants to own you. Cats are more territorial than any other animal. Besides peeing on things, (like dogs) they mark what is theirs by scratching (like deer) rubbing, and shitting (like humans.) Cats have scent glands in their cheeks, sides n' tails. But they reserve rubbing for things and people that they Really like.
4.) Same as a dog, a cat will roll over and expose their belly (vulnerable spot) when they trust you. Unlike a dog, that does not mean that you should rub their belly. Only do this when they know you very well and they are one of those cats that enjoy their belly rubbed. (some do, some don't, but you have to be friends with him/her before you should try it.)
5.) When a cat sits in touching range but does not beg for attention that means they see you as a fellow colony member, (Domestic feral cat group), so just chill and hang out with him/her. Don't talk/ pet/ cuddle the cat. Be cool and maybe do the slow eyeblink. Be cool, okay?