Well, skirmishers can be dealt with by fast lancers, the trick is to catch them as they are running away, I've found Prodomoi particually effective at this. Smash into them, withdraw immidiately and then strike again from close range, that usually breaks the low level levy skirmishers.

Oh, and mob the general at the start of the battle, especially Successor generals. Killing him makes all the difference.

As far as "hang in melee" goes, what exactly are you looking for?