To start with, don't forget: Countable, singular nouns need a determiner - the most common being articles (a and the) and possessives (my, her etc.)'. You have done this correctly for 'my dog' and 'my cat' (possessive pronoun 'my' is the determiner) but you have ignored all the ones with adjectives, such as 'kind person' and 'respectable lady'. So, how about having another look at your sentences and identify which ones contain a singular countable noun and then add a suitable determiner.

Your sentences are very nice, but I believe that there are two areas that need improvement: 1. ALWAYS start a sentence with a capital letter. 2. You have forgotten to add necessary articles: He's a kind person. She's a respectable lady. It's a great idea. You're a good leader. Your're a horrible person. You're a beautiful person. Remember that "a" means "one." You are referring to one kind person, one respectable lady, etc.

If there's one thing, and no possessive (eg. my), then you probably need "a". Many of your sentences are missing this important article. Also, pay attention to capitals and punctuation. He's a kind person. She's a respectable lady. That's my dog. This is my cat. - We normally don't refer to animals as he/she unless there'as a personal connection. Even then, presenting your pet for the first time sounds very strange if you suddenly call it he/she. Start with a neutral word (it, this, that). This is tasty food. It's a great idea. They're helpful people. They're cute cats. They're annoying dogs. They're good opinions. They're different kinds of food. We're hard workers. We're good friends. You're a good leader. You're a horrible person. You're a beautiful woman. If you pay attention to details like these, your English will become far better than most.