andsfkjkjdsd thank you ily (╥﹏╥) i really admire you so it makes me so happy to hear that you like my writing!
i'd like to add that since there's not really a universal standard of what 'good quality writing' is, i'd recommend that you look for people whose writing you personally enjoy and rp...
i started rping on a warrior cats forum at the ripe old age of 8 years old. i've been roleplaying kind of on and off since then but that's technically when i started. honestly i didn't even read warrior cats, i just made it up as i went along.
personally i write as much as i need to get in responses to other characters, the thoughts of my character, and to do something that helps to forward the story in some way. so it depends, but usually around 200-300 words. different types of roleplays elicit different post lengths though.