Nova? Dude, you should regularly be more worried about nearly every other AOE removal than Nova. I mean, sure, consider it and all, but how would you handle a flamestrike or desecration or any other number of AOE spells? Hint: It's the same rule for all of them. Don't stack minions.
Aggro mid-range more or less describes the entire current meta. It's funny that Priests have largely set this trend due to their removal spells, but are still largely under powered. I've always thought that getting rid of the 4 (say everything 4 or less and everything 5 and more change to the spells) spot would at once provide a buff for Priests and have the affect of completely changing the meta. Frankly, I don't think it would be an overpowered change either and it would probably be healthy in the extreme for every class.
That got a hair off track, so let's explain how you live at 4. There are a few rules that will make me, as a Priest player, wring my hands in frustration:
#1 Yes, try to stack 4 minions.
#2 In cases where you're not stacking 4 minions, try to ensure that you have multiple 5 or greater minions, generally through buffs.
#3 Don't buff any one card to the extreme. Spread your buffs, try to buff smaller minions to 4 when possible.
#4 Get rid of our Clerics immediately and make us top deck it.
#5 Many Priests don't play Thoughtsteal or Mind Control. I don't. I've tried, but I have found deck consistency to be far stronger than the occasional ability to grab something yummy from your deck.
#6 I'm totally going to steal your nice 2 or less attack minions with my Cabal. Pagel and a 4/5 on the board? DEAL! Think about that prior to playing such cards and consider building your deck with cards that do great for you, but not me. Those friggin' stealthed POS imps that Warlocks have! God I want them, but I can't have them!
Finally, try not to get hung up on the removal spells Priests have. Mages and Shamans have just as many ways to remove, and they're largely more versatile.
Edited by Musikaman on 2/12/2014 10:58 PM PST