Recently I found this item on the internet and whether you are playing Dungeons and Dragons or Pathfinder, Home-brew or Organized play, I think this is pretty interesting. Take a look at this post written by Grant of LookRobot blog. I can only whole heartedly agree with these points of advice.
http://lookrobot.co.uk/2013/06/20/11-ways-to-be-a-better-roleplayer/
Also see the other posts he made on his blog, most of which give pretty good advice.
http://lookrobot.co.uk/category/rpg/rpg-advice/