I echo almost what everyone wrote here so far!
When I first started, I was so excited about this new concept (RPing) so I didn't pay any attention to the character's backstory. I just played 'chaotically' in the first three terms until I started paying attention to my character's personality, reality and how they would react.
Writing-wise, don't even get me started
I was an immature writer and I believe I'm improving the more I play. This is another reason why writing posts will forever be my favorite way of playing.