StreamOfTheSky
Adventurer
So, here are some ideas I have to actually help the OP instead of thread derail. 
1. 3E tumble DC rules.
2. Abolish the Vital Strike line. For free, anyone that uses the attack action instead of the full attack action adds their BAB amount as a bonus to the damage. This is for two reasons: a) multiplying base weapon damage heavily favors people with giant swords of over-compensation +5, which IMO isn't the kind of style of combat you think of when you think of skirmishing; b) with wording like that, it could be combined with Spring Attack. Vital Strike explicitly cannot be.
Will make combat slightly deadlier at low levels. *shrug*
3.) Abolish the Step Up feat. Replace with something specific to spell and spell-like ability use if you must. Replace with "Defensive Sweep," after the high level PHB2 feat from 3E. It basically caused anyone that you ended your last turn next to that had not moved between turns to provoke an AoO for that. Drop the pre-requisites down to BAB +1, so just about everyone can have it. This will likely spur people to move around a bit more.
It's a start.

1. 3E tumble DC rules.
2. Abolish the Vital Strike line. For free, anyone that uses the attack action instead of the full attack action adds their BAB amount as a bonus to the damage. This is for two reasons: a) multiplying base weapon damage heavily favors people with giant swords of over-compensation +5, which IMO isn't the kind of style of combat you think of when you think of skirmishing; b) with wording like that, it could be combined with Spring Attack. Vital Strike explicitly cannot be.
Will make combat slightly deadlier at low levels. *shrug*
3.) Abolish the Step Up feat. Replace with something specific to spell and spell-like ability use if you must. Replace with "Defensive Sweep," after the high level PHB2 feat from 3E. It basically caused anyone that you ended your last turn next to that had not moved between turns to provoke an AoO for that. Drop the pre-requisites down to BAB +1, so just about everyone can have it. This will likely spur people to move around a bit more.

It's a start.