I'm going to run Dark Heresy 1st Edition. I'm a tolerably good GM, but my experience has been with systems with far fewer "fiddly" bits to remember (e.g., Savage Worlds). I've excluded (at least from the beginning) the expansion books to restrict the vast amount of Information I'm pretty sure I'm not going to remember.
Any thoughts on how to handle this - my concern is not being able to remember all of the skills, talents, combat rules, etc.