Showing Blast Range

Can someone tell me or mention a thread with good info on the best way to show blast effect circles on the map? Maybe an invisible token with a Aura? Or just a drawn circle prepared beforehand?

I have a couple things I use.  For some things I use the invisible token with an aura.  Mostly, this is just for things that aren't going to be visible for players (like the edge of some detection or warding effect), or that are large enough that the aura looks better.  If I want there to be a good visual shock for the players, I sometimes use one of the spell templates from the marketplace.  Just leave it on the GM layer until it gets triggered and then drop it on the token layer for all to see. For effects that are relatively common, I generally set them up with a character sheet so that they are already sized and available to drag and drop from the journal.