It used to scare me too. Best advice is just throw yourself in the deep end. Some Advanced want 5 paragraphs, others don't mind a little less, depending on their specifics mentioned in the rules. 

Try to find middle ground. I find that a very long page can be off putting and that most people wont read it anyway, especially if they are not involved in that post. So you're efforts are wasted. Whilst for conversations, reactions can be limited as you can only explain a characters actions so much in one paragraph without trying to mod the other roleplayer. 

Most Advanced members I've met are quite easy going though. :)