I went back to basics when I did my first AG. I wanted to make sure I wasn't doing anything too complicated so I could focus on following all of the steps correctly and as mentioned before, taking good notes. I would recommend a PA, something like you may have brewed one of your first times brewing with extract.
Other suggestions:
-Be sure to check gravity against what you would expect to get from the recipe you are using so you know your system efficiency for future batches.
-Have some boiling water and cold water available at mash in case you need to add some if you for some reason really miss your mash temperature, and have a ball park idea of how much you need to add per degree that you need to affect your mash. Nothing worse than yo-yoing above and below your target.
-On a related note, pick a recipe that has a moderate mash temperature, say 152, so if you miss your mash temperature by a lot, you can still adjust and at least get it to a range of 149 to 155 without severely thinning your mash. If you make a Scottish at 158 and you miss high (and don't catch it for 15 minutes), you could be deactivating enzymes.
-Write down everything you are going to do and in the order you are going to do it, even the stuff you have done dozens of times before, and follow your list. It is easy to miss something routine (like sanitizing your funnel for the fermenter) because you were so focused on getting the mash part right and forgot to do the simple things.
-Have a helper for the first AG brew, just for the extra set of hands. It's nice to be able to concentrate on getting it right and having a gopher get the stuff that you suddenly realize you need when your hands are full (expect the unexpected). Besides, it never hurts to have a drinking buddy while brewing.
-Start early in the day. I can regularly get from start to finish including clean up in four and a half hours now, but my first few AG batches went about 7 hours.
-If it hasn't been mentioned anywhere else, relax and have a homebrew.