There's not much advice I can give you. It's mostly experience that helps people get better. Also reading. The biggest key to becoming a better writer of any kind is to read, especially the classics. However, if you aren't too keen on that, just try to think about the smaller details. The sounds the sights, basically think of the senses. Also, try to reveal more about your character to give depth.
That's all the advice I can really give you, though its more then what I thought I would be able to. Of course, don't know how long my posts are going to be after what I got for writing that post. Honestly, all I wanted was a stupid Pokeball. Was that so wrong?