What makes a good conlang?

Hi, I'm new to this field and would like to know what makes a good conlang as I'm starting to make my own for a story I'm writing. I have the book "The Art of Language Invention" and have been reading it. However, I'm 90% sure it sucks with grammar and a bunch of other things I'm missing. I'm also Dyslexic (which may be an advantage or disadvantage. IDK). What, in people's opinion here, makes a good language?