Cheap answers like [card]Swords to Plowshares[/card], [card]Get Lost[/card], [card]Seam Rip[/card], [card]Oust[/card], and [card]Portable Hole[/card] deal with early creatures before they become a problem
If you want a casual Aurelia deck capable of taking a bunch of extra combats, I have a sample list you can try out on Moxfield
Build up your forces with Lathril and sacrifice them to effects like Ashnods Altar or Phyrexian Altar for the mana to hit your opponents with a large Return of the Wildspeaker or Walking Ballista
Check out all the Commander decklists here, courtesy of Wizards of the Coast.
Or if a tribe is nasty, or going to be a problem - go ahead and exterminate it
Play Style: Blues strength lies in its ability to counter spells , draw cards , and control the battlefield with bounce effects (returning creatures to their owners hands)