4. Actions are in 3rd person.Some perfectly good sentences get spoilt by confusing the 3rd person and the 1st person (narrative). Things like "Jacob slips down the path quietly, my hand on the hilt of my sword." Or "Alice walks over to Jacob and puts my hand on your shoulder." Roleplaying actions are always in the 3rd person. "Jacob slips down the path quietly, his hand on the hilt of his sword." "Alice walks over to Jacob and puts her hand on his shoulder." Also, remember that actions are in present tense or present continuous tense.
5. Assume makes an ass out of u and meInevitably, you might walk into a channel or room where the action is already happening. As there is no way of reviewing a log of a room you weren't in before, the only way you can find out the current situation is to ask OOC. There's been plenty a time when someone walks into a room and begins talking to everyone in it, whether they are within earshot or not! This not only disrupt the flow of RP, but annoys the other players as well.
6. Don't read mindsBe careful when responding to someone. First of all, make sure that your character can hear it! For instance, Jacob is thinking of ordering ale but doesn't say so aloud. You know for a fact that the bar is out of ale. What do you do? Nothing. You can't read minds, so you can't possibly know that Jacob wants ale. Don't make a reference to his thoughts in your own action, speech or thought. What goes on in someone else's head is their business!
7. Too much informationRead this description: "Clara is tall for her age, standing close to 6ft tall even though she is only 15. Her hair is long and brown, her eyes are hazel. She is wearing a pretty dress in her favourite colour blue. She has a little dog named Barky who follows her around. She lives in the forest nearby."
Let's assume you are seeing Clara for the first time. What is wrong with her description? Descriptions commonly refer to what you can see. Pick out the parts of Clara's description that you should be able to see – the hair, the eyes, the dress, the dog. And the rest of it? You won't know what her favourite colour is, what her dog's name is, or where she came from by just looking at her. Let's rewrite Clara's description:
"Clara is tall for her age, standing close to 6ft tall even though she is only 15. Her hair is long and brown, her eyes are hazel. She is wearing a pretty blue dress. A small dog follows her wherever she goes."
8. There is no such thing as an auto-hitCombat and spells are tricky things to do in a FFRP environment because of the lack of standard rules. Powergaming happens. You don't dictate what happens to the other character, even if you happen to be a powerful mage who has never casted a spell that didn't work in your AD&D game. Always allow an opportunity for the other character to respond. Never write "Alice conjures up a fireball and throws it at Clara, killing her immediately." That is plain unfair to Clara and Alice may soon find that no one wants to roleplay with her if she keeps that up. Writing "Alice conjures up a fireball and throws it at Clara" leaves an opening for Clara's respond. FFRP is a very poor place to pick fights, look for monsters to kill, or exercise any skill that would have a "forced" effect on someone else's character.