Okay, I think I want to finally try running PF. For the last 4 years I have mostly run 4e (with a little BX, AD&D, and the PF beginner's game mixed in). Prior to that I played 3.5 for a few months and back in the 80s I played a lot of AD&D. I still like 4e a lot but I want to take a break from it without getting away from D&D.
So any advice for an aspiring PF DM?
1) Only DM from a pre-generated module. Don't create the world yourself.
2) Make an 8th level character from scratch without a computer/excel file. Then go back and compare it to the computer/excel file and figure out the differences where you might have gone wrong. Do this for a few different classes, especially for classes that are likely going to be part of the campaign. I've learned a lot of rules this way.
3) Perhaps run a one-off game with some of those 8th level generated characters to get a handle on combat, attacks of opportunity, etc. The reason I say 8th level is because it's around there where it's semi-complicated and you'll encounter the vast majority of rules in combat and spellcasting. Make sure you are comfortable with the grapple rules and attacks of opportunity, as those are the two biggest pitfalls.
Probably covers the initial basics.
Thanks. I was thinking of running the Jade Regent AP.
One thing you might want to check out, if you're coming from 4e (and I assume your players have as well) would be to give the Mythic adventures rules a shot. It's an extra layer of complexity, sure, but it captures a lot of (IMO) the good parts of 4e, while still being very much PF, and it can help ease players in, since there's less of a culture-shock, as it were, between the two systems.
Since you're not new to DMing, this will provide less benefit than to others who are, but the Adventure Paths are a good place to get a feel for DMing the system. Even just looking through them to see how things tend to work in PF, as opposed to other systems.
Also, this will be a bit more intensive to DM; 4e was very DM friendly, especially with regards to creating new monsters, and PF is less so. It can be done, but it's more work.
Lastly, be wary about non-paizo material (and even some paizo material). There is a wealth of Homebrew and 3pp material, as well as 3.5 stuff that is supposedly "backwards compatible," but the problem is that with the wealth of material, there's a huge variance in quality and power level, and as a new GM unfamiliar with the system, it's wise to just stick with the Paizo stuff. Sure, some 3pp stuff may be just as good (and sometimes better, since often times the stuff is written to correct faults of the game, such as the underpoweredness of the rogue or monk, or the lack of certain key character options), but at least with Paizo, you have a lot of feedback right at your fingertips about whether a class or class feature will be problematic for your game.