I don't use alignment in my campaign.
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Have characters (PCs and NPCs) say and do stuff. The audience at the table can get the measure of them from that, just like in any other form of fiction.
On this I tend to agree with Grainger. Of my two active D&D campaigns, the default 4e one has PCs with alignments because that's what the rules called for, but they don't do much work (all but one is Unaligned, and the Good one is a (multi-class) cleric of Moradin which I think, by the rules, would require him to be LG); and if the PCs in the 4e Dark Sun game have alignments I don't remember what they are.For me, what alignment adds to D&D is a sense of the world as a battlefield. Minor conflicts are cast in terms of epic struggles between extraplanar forces, without which, I feel, the transcript of play, especially on the scale of the campaign as a whole, is perhaps less likely to result in an actual story.
As an aside...and I'm sure this will be a bit controversial to some
...I also believe that the idea of "DM as Adversary" is a D&D thing. A DM, IMHO, is someone who provides challenges in his world that the players PC's can/will face. A DM is *not* someone who provides fun in his world as defined as "situations where the PC's can be heroes and win". Somewhere along the line (mid through 2e if I had to guess) the game's idea that a DM was supposed to provide "challenges that the PC's should be able to overcome" became the mantra. This mutated into the abomination that is now "The DM is there to help the players have fun". There is a difference between the two ideas. The first, the more "old skool" idea of the DM providing challenges is that overcoming said challenges is FUN. The second, the more "new skool" idea of the DM providing "fun" is that unless the PC's overcome those challenges, the game is somehow "not fun".

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.