So while I'm blazing a trail of conquered land west through Carthage and Numidia, my nortern frontier (mostly old Seleucid cities,) keeps getting pounded by full-stack armies. Sometimes two at once.
These cities are fresh and need development so I can't crank out much beyond Nubian spearmen. So instead, I've relied on sallying out to break a siege. Not with a full-on conflict, but my sallying out once a turn with long-range skirmishers.
I don't have any Cretan archers, and I wouldn't risk such a great unit out there, but slingers are infinitely disposable and cheap. Chariot archers are amazingly adept at this stuff too.
Just skirmish. Chip away at the more vulnerable troops, and if you have an opportunity, try to rout dangerous stuff. Take pot shots at the general, try to rout elephants and scythed chariots, etc. When they charge, flee. A lot of the time, they'll try to respond with missile cavalry or marching up one unit of infantry. Mow down missile cavalry with chariot archers' melee charge and just keep your distance from infantry and take shots at them. In the long run, you can earn some valor for your ranged troops and if you cut down even just a hundred or so, it'll sometimes cause the besieging army to give up the fight.
If you're in an ugly situation where the besieging army isn't nearly so conservative as to let a band of slingers just drop infantry for free, you have to be careful, but it can be a good way to lure an army up into range of archers within the walls and within range of towers. If you don't mind watching them get chopped down, do it for the full thirty and exit the battle just before the time is up. Remember that in a sally battle, you don't lose for exiting the battle unless your units are still outside the gates.