The ranged bandits are really hard sometimes, especially in the beginning, after you get
enough cavalry only the larger groups mass of units can still be a problem.
Well, the tactic that worked for me so far is to have a lot of archers/crossbowmen, put them
on some high ground behind or around your spawn area (the bandits will always charge at you)
and use volley fire when the bandits are in range. That is one hell of an awesome feature,
each volley will kill almost everytime a few of them, looks awesome in the messages too!
Anyway, this will pretty much decimate them good enough while your infantry in front can block
their ranged fire. If you have cavalry, put them somewhere on the flanks, that almost always
breaks the bandits 'formation' (or at least they aren't just one bulk of units) and makes it
easier for your units to charge in after you pincushioned them. The best time for the charge is
the moment right before the bandits reach 'their range', meaning they always seem to stop at
a certain distant from your front line (except for their infantry of course).
For the steppe or desert bandits, try to use shieldwall with your infantry (pre battle orders!)
and let them run into it, then charge with them or cavalry. All the while archer behind firing
(thank god they can't teamkill

). Still early one it is just easier to simply avoid those groups for
the time being.
For the bandit lairs, they are really hard sometimes. Try to keep your guys close, going from one
spawnpoint to another or send them to each spawn, clearing one at a time. If you use ranged
yourself, try to pick the rear enemies while your guys battle the near ones. If your guys get
spread out, get them together again, otherwise the newly spawned units just gonna pick them
up one by one.
Otherwise there is always a little luck involved with some of the hideouts. For example the
sea raider ones are easier when most of their first wave spawns on the furthest ship/cave then
the ones nearer to your entry point.
Well, hope that helped a little.
