A good way of learning and improving your writing skills is to go back and re-read your old PBEM posts. On a PBEM game where the story always flows forward at a steady pace, where posts comes in from your fellow players every day, it can be difficult to find the time to reflect over how you are doing. This makes it very easy to get stuck in the same writing process and the same mindset. Remember, getting a lot of posts out is good and all, but it is even better if those posts are of great quality!
Taking an hour or so once in a while to sit back and read selected parts of your PBEM posts or just think about what you contributed to the story can help you achieve even more writing skills.
Some things to consider:
Were there any posts I wrote that I feel are bellow par in terms of quality?
Read those posts again (yes, it can be painful but it will be over in a second or so) and see what exactly makes you see them as bad posts. Did you rush through them? Did you focus too much on your own character? Did you make any misstakes with the story?
Then do the same thing with the posts you felt were the best you produced during the same time. What was it that made them so great?
Now would be a good time to write down a few notes, comparing the two categories. I did this with a bunch of old posts of mine, and I will share with you a few of the notes I made:
Bad posts:
Used only my own character to find something
No feelings
No open hooks for others to follow up on
Boring language
Good posts:
Described a lot of the surroundings
Left a really good hook for another player
Made the story go forward
As you can see, based on these short notes I can come to a conclusion about what I need to think about in the future. Next time I have a moment to do the same thing, I can see if I improved any.